The warm glow of a bright orange life raft lights up the pitch black night. A small hand opens the floating tent, revealing 11 people who stare wide-eyed at an approaching Turkish coast guard rescue mission.

A young girl clutches a doll as she climbs out of the motorless boat onto the Turkish ship. The rest of the group are pulled up to the deck.

"You really don't want to know what they've done to us," said Fatima Dhaiwi, looking over at her two daughters huddled under blankets.

"Definitely, definitely not going again."

Dhaiwi and the rest of the people on the ship tell CNN that they were forced back to sea by "masked men" after they arrived on Greek shores. Other migrants have also told CNN in recent weeks that they were pushed back from Greece, an accusation that Athens has repeatedly denied.

The United Nations' refugee agency (UNHCR) has also sounded alarms about "an increasing number of credible reports" of men, women and children being informally returned to Turkey after arriving on Greek land or waters in recent months.

Around 5,000 asylum-seekers have arrived in Greece since the start of March, according to the UNHCR.

That figure marks "a precipitous drop from previous years. Yet, the number of reported pushbacks, particularly at sea, has been rising," the agency says. 

It has called on Greece to investigate the reports.

On September 13, a Turkish coast guard ship granted access to CNN to observe search-and-rescue efforts along the north Aegean Sea.

The area accounts for nearly 50% of all sea crossings for migrants and refugees in 2020, according to the Turkish coast guard.

Since late February, 6,600 migrants were rescued at sea after being pushed back by Greek forces, according to the Turkish coast guard.

They were found by the rescuers in "punctured plastic dinghies with motors rendered unusable or on unseaworthy life rafts," the coast guard said in a statement on September 14.

The 11 people taken onboard the previous day are included in that figure.

The Dhaiwi family set off for Turkey from crisis-ridden Lebanon six months ago with hopes of shuttling through Greece and ultimately settling in Germany.

This was the family's fifth attempt at seeking temporary refuge in Greece.

"They grabbed me from my neck and started hitting me," said Dhaiwi, describing a confrontation on the Greek island of Lesbos in the north Aegean Sea roughly 12 hours after the family made landfall.

"They put a knife to my husband's stomach and they held a gun to my son's head."

CNN cannot confirm the identity or affiliation of the masked men.

Lesbos is home to Europe's largest migrant camp, which earlier this month was destroyed by a fire allegedly started by migrants protesting poor living conditions and Covid-19 restrictions in the settlement.

Saleh Dhaiwi holds up his hand, pointing at a wound he says was inflicted when he was shoved into the boat. The family members described being searched, and said their money and phones were taken from them.

The Dhaiwis' testimony is similar to that of others on the boat.

Ayat Abdi Ibrahim from Somalia said a group of men rounded up the migrants, breaking her spectacles and confiscating her medicines.

"Even animals are not treated like this," said Ibrahim.

"I didn't want anything from them, no money, nothing, I just wanted to get to my husband in any way possible."

Her husband has lived in Italy for five years. After the treatment she received on Lesbos, she says, she will not try to reunite with him again.

The Greek government defends its border policy, suggesting that the Turkish government has orchestrated media reports of pushbacks at sea as part of a disinformation campaign.

"Greece has every right as every sovereign state to defend its borders, we have a very tough but very fair border policy," Greek Prime Minister Kyriakos Mitsotakis told CNN's Christiane Amanpour in August.

"These types of reports are also an insult to our coast guard. The Greek coast guard has saved literally tens of thousands of refugees and migrants at sea."

But the UNHCR says it has collected multiple reports of pushbacks at its office in Greece. The UN agency has called for an immediate investigation into the alleged practices.

"Given the nature, content, frequency, and consistency of these accounts, a proper investigation should be launched without further delay," the UNHCR report said.

In response to CNN's queries about the alleged events of the night of September 13, the Greek Migration Ministry said it "always operates in full respect to International Law and European Regulations."

However, the statement did not acknowledge the incident as described by the migrants and the Turkish coast guard.

"We strongly deny any claims that the Hellenic Coast Guard engages in illegal 'pushbacks' in the Aegean Sea, and we point out that the source, as you mention, of these allegations is the Turkish Coast Guard," the Greek migration ministry said in a statement to CNN.

CNN has also been in close contact with an Afghan migrant, currently residing in the Turkish coastal city of Izmir, who has attempted multiple crossings into Greece.

Hamid Fazli, 23, said he attempted the sea crossing three times this year with his family. During two of those attempts, he says, the Greek coast guard violently pushed them back to Turkish waters

On May 16, Fazli asked for help from everyone he knew, including CNN.

After his rescue at sea, he sent video of their life raft showing the Greek coast guard in the distance. CNN was able to match the video filmed by Fazli to a Turkish coast guard report published on May 20 showing the rescue of a vessel after it was allegedly pushed back at sea while attempting to get to the island of Samos.

On August 16, Fazli, his wife and 18-month-old son were caught by Greek authorities after they arrived on Lesbos along with a group of Somali refugees, he said.

They say they were searched and all their money and belongings confiscated. Those who tried to resist were beaten up, he said.

They were told they would be taken into quarantine, but instead the group was moved onto a ship. They were then pushed onto a small raft and left in the open sea for several hours before being pulled out by the Turkish coast guard, according to Fazli.

"The water was very bad, a lot of waves, very dangerous and they do not see you are human," said Fazli.

"They don't give us anything (not) even a bottle of water for my baby."

CNN first met Fazli and a group of Afghans in March near the land border between Turkey and Greece. At the time, he said they arrived in Greece only to be captured, beaten up and had their belongings removed. 

Several migrants and refugees from Syria, Morocco, the Palestinian territories and Pakistan described similar incidents of violent pushback into Turkey at the land border.

Fazli said he will not attempt to seek refuge in Greece again.

"We are not trying to go back because they sent us back like that last time. I wish we can go there, I wish they would accept us."

Earlier this year, Turkish President Recep Tayyip Erdogan accused the European Union of not fulfilling its obligations under a 2016 deal with his country aimed at stemming the flow of migrants and refugees.

Turkey says it was left to shoulder most of the burden of hosting more than 3.5 million refugees on its own.

Turkish authorities then loosened border restrictions, a move that the EU criticized, accusing Turkey of exploiting refugees and migrants for political leverage.

At the time, the Greek Prime Minister accused Turkey of "weaponizing the issue".

But Greece's alleged pushbacks are a violation of international law as well as European regulations, according to migration experts and rights groups.

"When you push back people at sea, you endanger them and you are not complying with the obligation to have asylum proceedings," said Nele Matz-Luck, a professor at Kiel University and co-director of the Walther Schucking Institute for International Law.

"In the end it may be that there is no individual right to refugee status, but in the moment, the pushback operation violates the provisions in international law."

Back on the rescue boat, curled up in pain, Riham Sheim, a 27-year-old Palestinian-Syrian from the Yarmouk refugee camp in Damascus, echoes the sentiments of her fellow migrants.

"This was my first and last attempt," she said.

To Sheim, who had made a perilous journey from Syria, only the European Union can provide the safe future she seeks. But now she has given up.

"None of God's countries want us," she said.