An armed French police officer stands guard at the Franco-Italian border to check vehicles and verify the identity of travellers in Menton, France, November 15, 2015, after a series of deadly attacks in Paris on Friday. [Photo/Agencies]

BELGRADE/ZAGREB - The holder of a Syrian passport found near the body of one of the gunmen who died in Friday night's attacks in Paris was registered as a refugee in several European countries last month, authorities said.

The man, identified by Serbian authorities only by his initials A.A., came into Europe through the Greek island of Leros, where he was processed on Oct. 3, Greek officials said on Saturday. He was among 70 refugees who arrived on a small vessel from Turkey.

Serbian authorities said on Sunday the same man had been registered at a border crossing from Macedonia into Serbia a few days later.

The information is significant because if one or more of the Paris gunmen turned out to have come into Europe among refugees and migrants fleeing war-torn countries, this could change the political debate about accepting refugees.

"One of the suspected terrorists, A.A., who is of interest to the French security agencies, was registered on the Presevo border crossing on October 7 this year, where he formally sought asylum," the Serbian interior ministry said in a statement.

"Checks have confirmed that his details match those of the person who on October 3 was identified in Greece. There was no Interpol warrant issued against this person."

A spokeswoman for the Croatian interior ministry said the man was registered in the country's Opatovac refugee camp on Oct. 8 and from there he crossed into Hungary and then Austria.

"There was no (police) record about him at the time of registration and there was no reason for us to stop him in any way," she said.

Austrian Interior Ministry spokesman Karl-Heinz Grundboeck said however the assertion that the suspect attacker had passed through Austria had "no concrete basis."

"According to the latest information available, that is no more than conjecture and speculation," he said.

Any identity documents and fingerprint records would have to be matched with the remains of the attackers to establish whether they passed through various countries posing as refugees, or perhaps bought or stole passports along the way.

Greek government sources said a second suspect attacker was also likely to have passed through Greece.

Following the Paris bloodshed, populist leaders around Europe have rushed to demand a halt to an influx of refugees and migrants from the Middle East and Africa. Poland said it could not accept migrants under EU quotas without security guarantees.

Human Rights Watch's Emergency Director Peter Bouckaert said on Twitter the Syrian passport found may have been fake, adding such fake documents are widely available for sale in Turkey.

"The answer to the Paris attacks and the possibility that one of the attackers came by rubber dinghy to Greece... is not to shut the door on those desperately fleeing war," he said, calling for Europe to put in place a coherent asylum policy that would both help those on need and address security concerns raised by uncontrolled flows.

"People fleeing war need refuge. And trying to build fences and stopping them at sea only drives them deeper into the hands of criminal gangs, and drives them underground where there is no control over who comes and goes."