Hilary Benn, the environment secretary, broke cabinet ranks yesterday to warn that Heathrow’s controversial expansion plans should be rejected unless noise and air pollution are dramatically cut.

In an interview with The Sunday Times, Benn said Britain’s biggest airport had a “problem” with air quality even before the construction of the proposed third runway.

He cast doubt on claims by Heathrow supporters that new technology could solve the pollution concerns and said failure to cut emissions was “not something that we can contemplate”.

Benn’s outspoken remarks, placing the environment at the centre of the debate, expose the growing cabinet rift over the Heathrow expansion.

Earlier this month Geoff Hoon, the transport secretary, reluctantly postponed the runway decision until the new year after some ministers expressed private doubts.

Critics say the plan to increase aircraft capacity by almost 50% would boost emissions of harmful nitrogen dioxide and “particulates” – soot and dust.

There are claims that the airport’s expansion would also lead to more noise for the millions of families who live under the flight paths.

The official consultation document produced by the Department for Transport has suggested that stringent European Union emissions targets could still be met if the third runway gets the go-ahead.

However, serious doubts have been raised about the document’s conclusions after the Environment Agency issued its own report saying the case had not been proven.

The Sunday Times has revealed how the official data was manipulated by BAA, the airports operator that owns Heathrow.

In the interview, Benn explained how the airport already breached European limits on air pollution. While Britain had asked Brussels for special opt-outs from the regulations, the last of these so-called “derogations” would expire by 2015. “We have to honour that commitment and I am determined that we will,” he said.

Benn went on to warn of dire consequences if Heathrow still failed to meet the EU rules. “You are then in trouble with the commission, you get infraction proceedings and then off you go – which is not something that we can contemplate,” he said.

Benn’s remarks lay bare the growing tensions within the government over the issue. While Heathrow’s supporters in the cabinet, such as Hoon, pay lip service to the pollution and noise concerns, they prefer to concentrate on the economic arguments in favour of expansion.

In contrast, Benn did not say a word of support for the third runway during his 45-minute interview.

“The government has had a consultation,” he said. “We are currently looking at the results. What I have been looking at in particular is air quality and noise.”

He suggested the effect of a third runway on Britain’s overall carbon emissions was also a key issue.

While the environment secretary is the first cabinet minister to express his concerns about Heathrow in public, others are understood to have private doubts.

Ed Miliband, the energy and climate change secretary, is worried about the impact of airport expansion on the emission of greenhouse gases and was instrumental in forcing the decision on the runway to be delayed until January.

Harriet Harman, the Commons leader who represents Camberwell and Peckham in south London, is said to be worried about a potential backlash from voters in the capital whose lives could be blighted by the extra noise.

David Miliband, the foreign secretary, and John Denham, the universities secretary, are also said to have doubts. A Commons motion opposing Heathrow’s expansion has been signed by 57 Labour MPs including Martin Salter, the Reading West MP and a party vice-chairman on the environment.

The aviation industry has justified a third runway by claiming pollution could be reduced by the introduction of “green” aircraft over the next few decades and the wider use of electric or hybrid cars on the congested roads around Heathrow.

Benn pointed out that the airport must meet EU emissions targets well before improvements from new technology would have an effect.

Last night senior figures close to Gordon Brown dismissed Benn’s objections. “Air quality is an issue, but this project will get the go-ahead,” said a senior source.

Lord Mandelson, the business secretary, has recently begun campaigning behind the scenes to persuade ministers to support the project.

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