Athens (AFP) - A Syrian passport found by police at the scene of the mass shooting in a Paris concert hall belonged to an asylum seeker who registered on a Greek island in October, a Greek minister said Saturday.

"We confirm that the Syrian passport holder came through the Greek island of Leros on October 3 where he was registered under EU rules," said a statement issued by Nikos Toskas, the minister for citizen protection.

French police said the document was found "near the body of one of the attackers" in the investigation into the main attack of Friday's carnage, at the Bataclan concert hall, where 82 people were killed.

The authenticity of the passport was being checked, but its discovery indicates a possible Syrian connection which has been a working hypothesis for investigators after assailants hit six separate locations in Paris.

European security officials had long feared that jihadists could take advantage of the mass migration influx, mainly from war-torn Syria, that Europe has been experiencing since the beginning of the year.

A Greek police source on Saturday said Athens had forwarded to French authorities the fingerprints of the passport holder registered on Leros in October, to check whether he was the man involved in Friday's attacks.

They are not ruling out that the passport changed hands before the attacks.

"The most logical assumption is that it's the same person, sent on a mission to Europe," said a European security expert speaking on condition of anonymity.

"If this is established, it would be the first such case. In any event, this proves that the unchecked flow poses an unequalled challenge for European security. We simply don't know who is coming through," the expert added.

The Greeks were also examining a fingerprint from a second assailant provided from Paris, to check whether this person had also come through Greece, the police source said.

Greece's junior minister for migration Yiannis Mouzalas had admitted in September that it would be "foolish" to completely discount the possibility of jihadists sneaking into Europe among the refugee wave.

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Over 800,000 people have crossed the Mediterranean to Europe this year, with over 3,400 dying in the process.

But Mouzalas noted that the number of Europeans joining extremist groups in the Middle East was far higher.

"The opposite is happening. They leave from here and go over there," he said.

Prime Minister Alexis Tsipras on Saturday insisted that the refugees fleeing Syria "are hunted by the same terrorists" that struck in Paris on Friday.

"We must find solutions to the drama of the people who leave their homes, hunted by the same terrorists, and drown in the Mediterranean," Tsipras said in a televised address.