The science journal Nature reported claims on Monday that Romania's Prime Minister Victor Ponta had plagiarised large parts of his 2003 PhD thesis, which he denied, hinting at a political plot against him.
In a news article, Nature said it had seen documents compiled by an anonymous whistle-blower indicating that more than half of Ponta's 432-page law thesis on the International Criminal Court, written in Romanian, "consists of duplicated text".
"Moreover, the thesis was republished with very minor amendments as a Romanian-language book in 2004, and also forms the basis of a 2010 book on liability in international humanitarian law," said the report.
A former PhD student of Ponta's, Daniela Coman, is named as co-author.
Ponta told reporters in Bucharest that he was "ready to submit to any kind of verification".
He hinted that his political rival president Traian Basescu and his team might be at the origin of the allegations.
Ponta and Basescu are fighting to see who will represent Romania at the next European summit.
"I am used to this with Basescu. I guess he was angry at me and so he studied my PhD thesis", Ponta said.
"The fact that my thesis on the International Criminal Court is of interest to Nature is a bit comical", Ponta added. Nature is specialised in science and medicine.
The allegations come just a month after Ponta said his education minister Ioan Mang had resigned over allegations made by foreign researchers that he had copied scientific papers on information technology without attribution.
The prime minister had been forced to drop his first candidate for the education portfolio after she too was accused of plagiarism.
Hungary's president Pal Schmitt resigned in April and Germany's defence minister Karl-Theodor zu Guttenberg in March last year, also over plagiarism allegations.
Nature said much of the text in Ponta's work "seem to be identical, or almost so" to material in papers written in Romanian by two law scholars, and featured "direct Romanian translations of parts of an English-language publication" by another.
"It is very strange to be copying someone who signed your foreword", Ponta countered.
Romanian President Basescu named Ponta, who leads the Social-Liberal Union, to take over from Mihai Razvan Ungureanu whose centre-right government collapsed in April after a no-confidence vote.
Nature said Ponta obtained his PhD from the University of Bucharest while acting as secretary of state in the government of an earlier prime minister, Adrian Nastase, who was his PhD supervisor.