Climate change ministers and officials spent £1.5 million on flights in two years with £250,000 of the bill racked up on domestic journeys, research has found.
As well as tickets to far flung locations, the Department of Energy and Climate Change (Decc) team regularly booked seats between London and Aberdeen, where its North Sea oil and gas inspectors work. Flights from London to Manchester and Glasgow and between Aberdeen and Norwich, Southampton and Humberside were also recorded.
The TaxPayers' Alliance (TPA) research, based on requests made under the Freedom of Information Act, goes back to April 2010 - the month before the coalition took power - and runs to August this year.
It found some of the domestic flights were taken in business class, with one £460 ticket from Aberdeen to London, and two flights between Manchester and London that cost £188 each.
Since May 2010, the post of Energy Secretary has been filled by the Liberal Democrats, who want higher taxes on domestic flights "for which alternative, less polluting travel is readily available".
Matthew Sinclair, chief executive of the TaxPayers' Alliance, said: "Despite being one of the departments making air travel more expensive for people paying their own way, the Department of Energy and Climate has spent an astonishing amount of taxpayers' money on flights.
"This looks like breathtaking hypocrisy and extravagant waste from a department which can't be trusted with more and more of our money, while others work hard to make savings. Officials urgently need to explain why they spend so much money on so many business class flights in particular."
The most expensive of the 3,496 flights taken over the last two-and-a-half years was a business class booking from Cancun to London following an international climate change conference. Flights were also taken to Auckland, Cape Town, Nairobi, Jakarta, Washington, New York, Tokyo and Hong Kong. Business class tickets were booked for 362 trips at a cost of nearly £600,000.
A Decc spokesman said: "The department's international work, which includes securing the nation's future energy supplies, carrying out negotiations with other countries and international organisations on energy and climate change issues, and regulating the North Sea oil and gas industry among other things, means that sometimes air travel is unavoidable.
"Any such travel is for business purposes only, and we are careful to ensure that the most cost-effective and suitable flights are identified. This Government has never said people who care about climate change must not fly: it's not surprising that for some journeys, especially over very long distances when time is a factor, flying is the common sense option."