The office of José Manuel Barroso, the president of the European commission, racked up a €249,000 bill for private jets during the same period he attended the 2009 UN convention on climate change.
Barroso's jet bill for the nine-month period is just a small part of €7.5m worth of trips on private jets chartered by EU commissioners over the last five years, uncovered in research by the Bureau of Investigative Journalism.
The commission declined to comment on the specifics of the spending on private jets, other than to confirm €249,000 was a private jet spend for 2009 for the president's office, but refused to say whether he took such a jet – which releases around 55 tonnes of carbon dioxide each transatlantic flight – to the convention itself.
The bureau found that Barroso and 35 others spent €28,000 at the luxury Peninsula New York hotel during the visit to the UN climate change convention. This figure was confirmed by the commission.
The research also uncovered public money being used to fund a €75,000 cocktail party at a science conference – Discovery 09 – which was "filled with wonder like no other ... with trendy cocktails, surprising performances and top DJs", as much of the EU was in the grip of recession.
The commission funded €300,000 worth of events described in internal documents as cocktail parties in the same year. At least a further €1.2m was spent on hotel and conference costs in 2009, including stays in San Diego, Prague and Balmoral.
An additional €20,000 was spent on gifts for commission guest speakers since 2008, including cufflinks, fountain pens and Tiffany jewellery.
The findings will further raise tension in negotiations over the commission's bid for a 4.9% budget increase next year, which the British government has already vowed to oppose.
The examples of commission spending have also drawn criticism from EU parliamentarians in other countries. "It is extremely disappointing to see how easily the commission spends the EU taxpayers' money on private jet travel and luxury hotels," said Martin Ehrenhauser, an independent Austrian MEP who helped uncover details of the spending.
The study also showed the continued lack of transparency in how the commission spends its money. More than €42m of transfers to "natural persons" – individuals, whose names the commission keeps private – were found between 2007 and 2009, though these had fallen from €27m in 2008 to just over €1m in 2009.
However, a further €381m was spent on "confidential" activities, which the commission refuses to disclose for security reasons. The degree of confidential spending in 2009 was more than double its 2007 level, at €221m.