Business leaders have welcomed a report which says a third runway at Heathrow would add £30bn to the UK economy.

The British Chamber of Commerce (BCC) claimed the controversial project would increase productivity by up to £12.8bn, and create £20bn in wider economic benefits over 60 years, such as higher levels of employment.

The BCC also said it would cost the country £1bn every year the runway is delayed.

But anti-expansion campaigners slammed the report, saying it ignored environmental costs and the impact on residents’ quality of life.

Susan Kramer, MP for Richmond Park, said: “I have talked to many businesses about the issue of Heathrow expansion, and I have never been told about any member of staff who missed a vital meeting because they were unable to get a flight to where they needed to go.”

John Stewart, chairman of campaign group Hacan, argued that the report contradicted previous findings, saying the Government’s own figures suggested the benefits to the economy would be £5bn over 70 years.

He said: “Overall, this report smacks of desperation. It comes to something when a body such as the British Chamber of Commerce resorts to sensationalist claims that each year the third runway is delayed costs the country £1bn. It is a sign they have lost the battle for a third runway.”

David Frost, director general of the BCC, said: “This comprehensive study clearly outlines the economic benefits of expanding Heathrow - an important part of the debate which too few people fully understand.

“Connectivity is vital to the UK economy as businesses seek to develop new global opportunities that will allow them to generate wealth and jobs. Without additional capacity at our major hub airport, we will continue to fall behind our continental competitors.”

Brendan Barber, general secretary of the Trades Union Congress, and Tony Woodley, general secretary of union Unite, said a third runway would help safeguard jobs in the UK.

Mr Woodley added: “Today we stand at a crossroads where we can take the difficult decision and expand Heathrow and compete or not expand and begin the slow decline of steadily losing destinations served by Heathrow and the jobs that are associated with them.”