Britain's ambassador to Washington denied on Saturday claims that he helped Libyan leader Moamer Gaddafi's son with his doctorate.
The Foreign Office in London confirmed that Sir Nigel Sheinwald met Seif al-Islam during his time studying at the London School of Economics university but insisted he had no part in writing his thesis.
The denial comes as the LSE investigates claims that Seif plagiarised part of the thesis.
The Daily Mail newspaper quoted a senior LSE source who claimed Sheinwald had shown a "profound interest" in Seif's studies and offered "active assistance" in his work.
The source said the alleged assistance was informal and legitimate, the tabloid reported.
"Seif was simply using his impressive contacts to make sure the work he produced was of the highest quality," the Mail quoted the source as saying.
Sheinwald was at then prime minister Tony Blair's side when he first met Gaddafi in 2004, and again in 2007.
Sheinwald has been Britain's ambassador to the United States since 2007 after being appointed by Blair.
In a statement, a Foreign Office spokesman said: "Sir Nigel Sheinwald did meet Seif Gaddafi during the time he was studying at the LSE, and was therefore aware that he was preparing a thesis.
"But Sir Nigel had absolutely no role in the writing of any part of the thesis, made no suggestions about it to Seif Gaddafi or anyone else, and suggested no changes."
Seif graduated from the LSE with a masters in philosophy, policy and social value in 2003 and a doctorate in philosophy in 2008.
However, the institution is looking into claims that he plagiarised sections of his doctoral thesis.
Additionally, the LSE's council has set up an independent inquiry into the university's relationship with the Libyan regime.
LSE director Howard Davies quit last month over the LSE's links with the Gaddafis, saying the university's reputation had "suffered".
Davies admitted the decision to accept £300,000 ($485,000, 340,000 euros) in funding from Seif, was wrong and that his trip to Libya to help modernise the regime's financial institutions was ill-advised.