UNIONS lambasted the government yesterday over its “overtly political” deferral of a decision on Heathrow’s hugely controversial expansion.

Transport Secretary Patrick McLoughlin said he “hoped” that the government would be in a position to choose between the options at Heathrow and Gatwick airports by next summer.

The announcement of the postponement was welcomed by environmental groups and local campaigners.

But critics said it was a politically motivated move to avoid a damaging by-election after Tory London mayoral candidate Zac Goldsmith vowed to quit as an MP if one of the two options at Heathrow is approved.

GMB national officer Mick Rix said: “So much for David Cameron’s pledge to deliver the much-needed infrastructure projects.

“While this decision has been dressed up as giving time for consideration on environmental impacts and the best possible mitigation measures, the reality is that he has run away from the political threats from Zac Goldsmith.”

The union says 76,000 people are employed directly at Heathrow, with another 38,000 local jobs relying on the airport.

TUC general secretary Frances O’Grady said the repeated delays meant that “the British people will lose out on new jobs, new apprenticeships and economic growth.”

Before becoming Prime Minister, David Cameron promised: “No ifs, no buts, there will be no third runway at Heathrow airport.”

Opponents of the expansion also attacked the delay in reaching a decision.

Shadow transport secretary Lilian Greenwood charged that it “owes more to political calculations than genuine concern for the environment or residents who now face another year of blight and uncertainty.”