The verdict of the commission contradicted that of a council set up by the education ministry, which on Thursday cleared the centre-left premier’s name after a first finding against him in June.
According to the university panel, about a third of the pages in the 2003 thesis, which was about the International Criminal Court in The Hague, were directly copied from other writers.
“This massive plagiarism cannot be explained by different editorial rules” held by Ponta to apply in 2003, the commission found.
“Rules of good conduct existed in 2003, they have in fact existed for more than 200 years,” said panel president Marian Popescu.
Ponta fired back on Friday, charging that “this is a political decision, handed down by a commission set up especially for me,” according to the Mediafax news agency.
“It’s the only commission which did not invite me to express my point of view.”
The panel’s Popescu said that the rules had provided in 2003 for “correctly citing passages produced by other authors, using inverted commas and footnotes”.
The way Ponta’s thesis was presented “bore witness to the temptation to copy”, he added.
Romanian Academy president Ionel Haiduc concurred on Realitatea TV channel, saying: “The body which granted the doctor title is best qualified to rate a thesis.
“The university’s decision will be followed more closely by academics than that of any other committee,” he added.
University dean Mircea Dumitru announced that he intended to submit the report to the institution’s senate, which awarded Ponta’s doctorate and which can propose that it be withdrawn.
The final decision rests with the education ministry, Dumitru said.
Education Minister Ecaterina Andronescu had so far failed to react to the latest developments in the case but recently warned that the relevant university body could be closed if the ethics panel confirmed the plagiarism.
Several professors branded her statement as a barely veiled threat.
On Thursday, the national council of ethics, whose make-up was changed by the education ministry shortly before Ponta’s government took power in May, said that his thesis “respected the academic requirements” in force in 2003.
When challenged in June by an academic commission, Ponta denied the allegations, saying rules in force in 2003 did not require using quotation marks when reproducing parts of other authors’ works as long as they were mentioned in the bibliography.
At the time the national council certifying university degrees (CNATDCU) revealed that “85 of the thesis’s 307 pages were copied literally from other works”.
The CNATDCU had published its conclusions in spite of then education minister Liviu Pop’s heavy-handed reaction. He on the same day announced the council’s dissolution while forcing his way into the room where council members were analysing Ponta’s thesis.
In an interview with Spain’s centre-left daily El Pais, Ponta said last month he would resign if found to have plagiarised his thesis but he went back on his statement a few days later.
Germany’s former defence minister Karl-Theodor zu Guttenberg resigned in March last year after doubts over his doctoral thesis. The university of Bayreuth later found the plagiarism to have been deliberate.
Hungarian president Pal Schmitt, a close ally of right-wing Prime Minister Viktor Orban, stepped down the following month after being stripped of his 1992 doctorate for copying other people’s work and claiming them as his own.