Lionel Messi has agreed a two-year deal with Paris St-Germain to join the French club following his shock exit from Barcelona, says BBC Sport columnist Guillem Balague.

The deal is subject to a medical.

The 34-year-old Argentina captain left Barca - the only club he has ever played for - as they were unable to afford a new deal under La Liga's financial fair play rules.

Mauricio Pochettino's PSG finished second to Lille in Ligue 1 last season.

"It's all been confirmed. Lionel Messi is going to be a PSG player," Balague said on BBC Radio 5 Live. "That's it, it's done. It's happened in the last few minutes.

"At the moment there are as many police as there are fans [at the stadium]. That's going to change soon. There's eight cameras here, again that's going to change. It seems like it is a two-year deal, plus one.

"His idea was to do it at Barcelona but it's going to be PSG. Then if he feels OK he will stay one more year maybe. But in any case his aim is to be at PSG and then to do well in the Qatar World Cup."

Considered one of the greatest players of all time, Messi scored a record 672 goals in 778 games for Barca, the club he joined as a 13-year-old.

He won the Ballon d'Or a record six times and lifted 35 trophies with the Catalan club.

The signing of Messi - who would be reunited with former Barca team-mate Neymar at the Parc des Princes - is one of the most noteworthy captures in football's history.

Unless there are any late hitches, he will become PSG's fourth free-transfer signing this summer after the arrivals of midfielder Georginio Wijnaldum, defender Sergio Ramos and goalkeeper Gianluigi Donnarumma.

Highly rated right-back Achraf Hakimi also joined from Inter Milan.

Messi had agreed a new deal - on 50% of his old wages - to stay at Barcelona but the club could not afford to implement it because they were so far above the wage limit allowed by La Liga.

"He used to earn 140m euros gross a year at Barca, that's around £125m," said Balague. "Take off about 40-50% for tax.

"He agreed to stay at Barcelona by reducing his wages by 50%, not more than that because that's illegal to do so [under Spanish law]. Basically, the league wouldn't believe he was reducing his wages to zero, which is what Barcelona may have tried to do as they are €1bn in debt. Basically, they cannot afford him."

If the deal goes through quickly, he could make his PSG debut at home to Strasbourg on Saturday.