A huge flow of migrants through Turkey could threaten social unrest in Greece, warned EU Justice Commissioner Jacques Barrot.

"There is a major threat to the equilibrium of the Greek democracy because of the uncontrollable flow of immigration," Mr Barrot told a press conference in Brussels.

Athens has accused Ankara of failing to stop clandestine immigration through Turkish territory which the Greeks say has pushed their resources to the limit.

Greek Interior Minister Prokopis Pavlopoulos this week said the number of migrants detained in Greece tripled from 40,000 in 2006 to 148,000 last year.

Europe's asylum legislation puts pressure on the first EU country that receives applicants to handle their claims but the rules could change in the next six months.

Immigration is causing social tension in Greece and is used as an argument by the extreme right which saw its share of the vote rise to seven per cent in recent European parliamentary elections.

Mr Barrot visited Greece this week and called on Turkey to do more to tackle clandestine immigration.

"Turkey has to help us fight the facilitators and the traffickers who push people to make risky journeys," he said in Brussels.

"We can't simply remain motionless. We have to get much firmer control from the Turkish government. We would also encourage the Turks to sign a readmission agreement," the French commissioner said.

He added that he would like to see readmission agreements with Pakistan and other Asian nations, from where some would-be migrants begin their journeys.

Mr Barrot said he intended to re-launch debate on immigration during an informal meeting of EU interior and justice ministers in Stockholm on July 15 and 16.

EU nations Cyprus, Greece, Italy and Malta are in the front-line of the battle against migrants without papers and are gearing up for the summer wave of arrivals by sea.

Other EU nations refuse to be constrained to accept numbers of asylum seekers to help the four, with some stressing that they have to concentrate on the EU eastern borders in the former Soviet Union.