Several universities welcomed an Israeli professor into their lecture theatres when he impressed them with his doctoral thesis in international law.

The academic, known only as Mariusz K, began a series of lectures across Poland earning up to £100,000 zloty (£25,000) from the various schools and colleges.

But the man arrested in Krakow recently was neither Israeli nor qualified to teach, according to police.

The “Chasidic Jew” they arrested, complete with black suit, kippah, a beard and sidelocks, was said to be as bogus as the qualifications he forged.

And the hundreds of students he taught have already been forced to re-sit their exams.

Mariusz, 46, was arrested following a two-year search to find him after he disappeared from one of the universities when staff became suspicious.

He had begun his lectures in February 2010 after presenting himself to Lazarski University in Warsaw, the University of Natural Sciences and Humanities in Siedlce and the Higher School of Business and Social Sciences in Otwock. As well has his bogus ID and fake qualifications, he also presented documents apparently signed by government officials and a recommendation letter from a foreign university, according to Rzeszpospolita newspaper.

The district court in Warsaw issued an arrest warrant two years ago and, at the time of his arrest, he was enrolled in the Jewish studies department of the Jagiellonian University in Krakow.

Police are now probing why he decided to pose as an Israeli citizen, and where he obtained his false documents.

He faces charges of fraud and using forged documents. If convicted, he faces up to eight years in prison.