Thousands of villagers in the southern Indian state of Tamil Nadu are fighting a proposal to expand a port owned by billionaire Gautam Adani, one of the world's richest men.

The villagers, most of whom make a living through fishing, say the port expansion in Kattupalli - a small village located in Tiruvallur district along the Bay of Bengal coast - would submerge their lands and wreak havoc on their livelihoods. Adani Ports denies this.

The 330-acre multi-purpose port - originally built by Indian conglomerate Larson & Toubro (L&T) - was acquired by Adani Ports in 2018.

The company later proposed to expand it more than 18-fold to an area of 6,110 acres by claiming portions of land along the coast.

According to the company's master plan, the expansion would increase the port's cargo capacity from 24.6 metric tonnes to 320 metric tonnes per year and develop new rail and road networks that would boost trade connectivity in the region.

But fisher people in at least 100 towns and villages located on the coast say this would gravely impact their work. "The number of fish varieties found here has already gone down significantly. Any kind of expansion would further deplete its population," claims Rajalakshmi, a fisherwoman from the region.

The expansion has met with resistance from environmentalists as well, who claim the plan would lead to massive coastal erosion and a loss of biodiversity, especially of the indigenous fish species and the crabs, prawns and small turtles found in the region.

Environmentalist Meera Shah claims it could also "destroy" Pulicat lake, the second-largest saltwater lake in the country.

At the moment, the coastal stretch acts as a barrier between the lake and the Bay of Bengal. But the region has been experiencing widespread environmental pollution and coastal erosion in recent years, Mr Shah added.

If more construction is undertaken here, the coast would shrink further, "leading the lake and the sea to merge".

A spokesperson from Adani Port, however, rejected the allegations and called them "misplaced".

A senior company official, who wanted to stay anonymous, told BBC Tamil that locals "are not against the expansion of the port" and alleged the protests were being led by people "with ulterior motives for publicity".

"Individuals opposed to the expansion do not base their claims on any primary data. Some good NGOs involved in protecting the environment may have some genuine questions, which will be addressed during the [mandatory] environmental clearance process," the official added.

Protests against the port expansion first broke out in 2018 and have continued intermittently over the years.

The agitation intensified again in September, when the state government started the process of giving environmental clearance to the project, paving the way for the expansion work to begin.

In the same month, the state's Pollution Control Board was forced to postpone a mandatory public hearing for the project amid strong protests.

According to the master plan, of the 6,110 acres needed for the expansion, 2,000 acres would be acquired from the sea, while the remaining land would be taken from the coastal area.

The company says it will reclaim parts of the sea by filling it with sand and include them in the port area. It also plans to deepen a portion of the sea and create a sea wall around it so that more ships can move along the coast.

Experts warn this could have devastating consequences for the region's ecology.

The east coast of India - and the Tamil Nadu coast in particular - does not have the geographical landscape suitable for port construction, let alone an expansion, claims Dr Ilango Lakshmanan, a professor of hydrogeology at the Indian Institute of Technology (IIT) Madras.

"This would disrupt the coastal topography and lead to more sea erosion," he added.

A senior company spokesperson rejected the claim and said that sea erosion in the region could not be linked to the port's construction alone.

"States like Gujarat and Maharashtra, where some of the major ports in the country are located, have lower rates of sea erosion compared to the east coast," the spokesperson said.

But some industry experts also say the expansion plan should not be dismissed entirely as it would benefit the state's economy and bring more employment.

"Kattupalli port was facing losses and started making profits only after the Adani takeover. An expansion would bring in more ships, which, in turn, will increase its economic scale," Valliappan Nagappan, the former president of Hindustan Chamber of Commerce, an independent trade organisation, said.

"However, the company must ensure that locals are well-compensated and relocated [if required] properly, without any impact on their livelihoods," Mr Nagappan added.

But protesters say they are not convinced.

"We are ready to face anything in our fight against the project. Our livelihoods should be protected at all costs," Vijaya, a fisherwoman from Pulicat, said.

Protesters blame the Tamil Nadu government for not doing enough to safeguard their interests.

Many claim that before the state elections, Chief Minister MK Stalin repeatedly promised he would scrap the expansion plan, but nothing has happened since he came to power in 2021. The BBC has reached out to the chief minister's office and the state's environment minister for comment.

This is not the first time that a port run by Adani Ports has invited protests.

In 2022, massive protests erupted in the fishing villages of the neighbouring state of Kerala against the construction of a port managed by the company in partnership with the local government.

The protest was later called off in December after the state government promised to pay each of those who were to be displaced a monthly compensation.

At Kattupalli, port authorities have been wooing the local community by offering them free medical aid and promising them jobs.

"We are in touch with the villagers and communities around the port area and they are very much interested in the project and getting jobs," the unnamed Adani Ports senior executive cited above said.

The protesters, however, say that they are being cautious.

"If they want to give us medicines and take our land, we will not let it happen," one of them said.