Spending by the Metropolitan Police on air travel has risen by more than a third in a year, with the amount spent on business class tickets alone exceeding the cost of all flights in the previous two years.

Figures obtained by The Independent show that Britain's biggest police force spent £6.2m on flights in the most recent financial year, a 35 per cent increase on the £4.6m spent on air travel in 2007/08 and 06/07. Of the £6.2m, £4.7m was spent on business class flights.

The figures have brought criticism from members of the Metropolitan Police Authority (MPA) who have queried why, in the midst of a recession and with a shrinking budget, Scotland Yard has increased its own costs by voluntarily paying for more expensive air fares.

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The total figure, released under the Freedom of Information Act, covers the cost of 6,316 trips made by Metropolitan Police officers and staff last year. Of that number, 2,246 trips – 35 per cent – were taken in business class. Those flights totalled £4.7m, meaning that officers within the Met took the equivalent of six business class flights every day last year at an average cost of £2,090 per ticket.

The force has stressed that the number of business class flights is relatively low compared with the 4,070 taken in economy class last year. But the business class tickets accounted for 74 per cent of the overall air travel costs while the economy tickets, costing a total of £1.5m – an average of £368 each – made up just 26 per cent of the total spend, despite accounting for 65 per cent of the trips.

Jenny Jones, the Green Party member of the Metropolitan Police Authority, said: "For me there are two issues here: first of all we need to ask if all of these flights are actually necessary or if the Met should be looking at cutting the number of flights they are taking. Secondly, when the budget is in such dire straits, they should be looking to cut superfluous costs such as business class seats, when economy ones will do."

Examples of recent flights taken by the Met include a trip last month by Sir Paul Stephenson, who visited police officers in India. Most memorably, John Yates, the assistant commissioner is charge of counter-terrorism, was dispatched to Brazil in 2005 to apologise to the family of Jean Charles de Menezes after the electrician was wrongly shot dead by Scotland Yard officers on a Tube train.

But figures obtained by this newspaper also show that a large amount of the force's flying is done within the UK. Of the 6,316 flights taken in 08/09, 1,958 – five a day – were UK domestic flights.

This has prompted outrage from environmentalists who are angry at the number of flights taken by the force from one British airport to another.

Leo Murray, a spokesman for the campaign group Plane Stupid, said: "It is a mystery why any police force should be taking any domestic flights at all. But a single police force suddenly deciding to spend taxpayers' money taking five flights every day is a kick in the teeth for all of us doing our best to reduce our carbon footprints. Domestic flights are driving expansion by clogging up our airports, yet the vast majority are totally unnecessary. Hasn't the Met heard of teleconferencing?"

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The number of UK internal flights is higher than the 1,645 taken in 2007/08, a number which included 11 flights to Southampton, 90 miles from London, and 496 flights to Edinburgh.

Ms Jones added: "I have repeatedly said that the Met has got to reduce the number of internal flights in Britain, partly because of the environmental issues, but also because of the cost. They really should be using the train for business trips within the UK. At a time when the budget is stretched, the Met has to start acting responsibly."

A spokeswoman for the Metropolitan Police said that the reason for the increase in the amount spent on flights was "investigation and security work". She added: "In all instances, the most economical fare is purchased that meets the needs of the traveller and the reason for the visit.

"Authorisation for all overseas trips is made by an officer of at least ACPO Commander rank or a senior member of police staff in overall charge of a business area. Every trip requires a strong business case and the authorising officer determines what class of ticket needs to be purchased.

"We have a number of deals with airlines to help drive down costs. The Metropolitan Police always seeks to book the cheapest flights available bearing in mind operational demands.

"Almost three-quarters of all flights taken last year were economy class. The default position for all staff and officers is economy except where security, operational or protection requirements apply."