The chief of the association representing private job agencies in Greece, Athanassios Kottaras, said he received six or seven complaints every week (they were almost unheard-of just two years ago) from Greeks moving abroad for jobs that turn out to be nonexistent or exploitive. Mr. Kottaras has appeared several times on Greek television to raise awareness about the problem, which he attributes to hundreds of illegal job agencies.

The head of Greece’s state labor inspectorate, Michalis Kandarakis, said there were about 300 such illegal job agencies in Greece, compared with the 90 legal ones represented by Mr. Kottaras. But he said closing them down was difficult, as they often changed names, staff and premises to elude the authorities. “They even lodge charges of harassment or attempted blackmail against inspectors to slow down the process,” Mr. Kandarakis said.

The Greek Orthodox association in Melbourne, Australia, has published a warning on its Web site after receiving “numerous complaints” from Greeks “in regard to certain unscrupulous individuals that seek to take advantage of prospective migrants.” The site warns against professed migrant advisers who are “seeking exorbitant amounts of money for the purpose of issuing visas and finding employment.”

Official efforts to combat the swindles are often hampered by the victims’ reluctance to report their experiences to the authorities.

Vangelis Kouris left the Greek capital for Oslo last month after his bakery business collapsed and efforts to find work failed. But a job packing fish in a Norwegian factory, proposed to him by Greeks at a cafe near his neighborhood in Athens, did not exist. Neither did the factory. Mr. Kouris, 45, has since been sleeping at Oslo’s main railway station as he looks for work, anxious to raise some money for his wife back home, who has bowel cancer and cannot afford medical tests, he said.

But he has refused to alert the authorities in either country out of fear that he will be ordered back to Athens. “I had a bad experience,” Mr. Kouris said. “But I have to stay and try my luck here. There’s no work back home, nothing.”

Ioanna Zacharaki, a social worker based in the German city of Düsseldorf, reported an alarming influx of Greeks seeking work, adding that many claim to have been duped in job frauds. Working with other local Greek immigrants, she has organized concerts and other events to raise money to pay for return flights for those who want to leave and hotel accommodations for those who insist on staying. But she is reluctant to report suspicious cases to the police. “People are obviously making a commission in these exchanges, but what do you tell the authorities? You don’t want to get mixed up in anything,” she said.

The worst thing, according to Greeks in destination countries, is that those exploiting the hopeful emigrants are generally Greeks. “Swindling your compatriots when they’re down on their luck,” Ms. Zacharaki mused. “I never thought I’d see it happen.”