Manchester Airport will double the number of flights it handles and become as busy as Heathrow is today, the government has predicted.

According to the official forecast, there will be 449,000 take offs and landings at Manchester by 2050 – up from 213,000 in 2005.

It would mean a flight taking off or landing on average every 70 seconds.

The forecast was published in a report to the Committee on Climate Change and has been described as ‘shocking’ by opponents of the airport’s expansion.

Campaigners warned that the surge in air traffic would lead to another terminal being built at Manchester, although airport chiefs denied the claim.

The Department for Transport put forward the predictions as part of efforts to determine Britain’s carbon dioxide emissions. They predict Manchester will be the fastest growing of the four biggest airports in Britain and will overtake Gatwick to become the second busiest. By 2050, it is predicted to handle as many flights as Heathrow does now.

But Heathrow is also forecast to expand, albeit at a slower rate than Manchester, and will still be the country’s busiest airport, with just over 700,000 flights.

Lib Dem councillor Martin Eakins, who has campaigned against airport expansion, said: “Nobody I’ve spoken to was aware of the extent to which Manchester Airport hopes to expand, indeed those I’ve told are both shocked and stunned by the news. The wider community should be consulted as homes under or near flight paths will surely lose their value due to the increased noise and pollution.

“Manchester council, which jointly owns the airport, should come clean and assess the impact these extra flights would cause before pressing ahead.”

Robbie Gillett from the Stop Expansion at Manchester Airport pressure group said: “It’s time to update our thinking about airport expansion. We need to create jobs in low carbon industries and move away from this ‘all-growth-is-good-growth’ mentality.”

The figures are included in a report by the Committee on Climate Change. It warns that Britain’s aviation demand could grow more than 200 per cent over the next 40 years and the number of passengers could rise from 230m to 695m per year.

That would threaten the government’s aim to keep carbon dioxide emissions at or below 2005 levels and put Britain 600,000 take-offs and landings over the target limit.

A Manchester Airport spokesman said: “We welcomed the report published by the Committee on Climate Change and as an industry pledged again to reduce levels of carbon dioxide emissions substantially in the years ahead. Aviation holds a key role, not only in providing essential transport links that enable economies to grow, but in bringing important benefits to society, the value of which should not be underestimated.”