Pressure is mounting on the Government after a "damning" Parliamentary report shows it has not proved the Heathrow expansion can achieve legal environmental limits.

The report, issued on Thursday, February 23, by the cross party Environmental Audit Committee, is a follow-up of its first report and states it has seen "little evidence so far of the 'step change' in the Government’s approach to environmental mitigation", which the committee had originally called for.

In the report, the committee calls on the Government to set out an approach on how it will keep up with the most up-to-date air quality guidelines and to provide an "emissions reduction strategy" that will allow the UK to meet its carbon budgets.

The committee also asks for assurances that effective noise mitigation measures will be enforced.

According to the report, the Government has failed to do any of these things, which has strengthened the resolve of the four councils- Hillingdon, Richmond, Wandsworth, and Windsor- campaigning against expansion.

Lord True, Leader of Richmond Council, said the report is "yet again more evidence" the Heathrow expansion is not feasible and urges the Government to give up its plans.

He said: "Heathrow already contributes to illegal pollution levels.

"And, the Government has no realistic plan to combat this.

"Expanding Heathrow would not only be damaging to the environment, but it would damage the health of tens of thousands of Londoners."

"The Government needs to stop the spin and come clean on the real impact of expansion."

Leader of Wandsworth Council Ravi Govindia said the plans will "never pass a simple legal test on air quality”.

He added: "It’s wrong on every level, legally undeliverable and will end in failure after years of wasted effort.

"Nothing is going to change between now and 2018 to make this scheme any less polluting so ministers should face up to this truth now and abandon their plans for a third runway."

A Heathrow spokesperson said: "The Airports Commission was clear that Heathrow can be expanded while reducing noise for local communities, in accordance with air quality requirements and is compatible with the Government’s carbon goals for aviation.

"Heathrow is determined to operate and grow our airport sustainably and we look forward to working with all stakeholders throughout the planning process to ensure that an expanded Heathrow meets these objectives.

"For example, we’ve committed to work with others to transform public transport to tackle the real source of emissions – road vehicles – and will insulate up to 160,000 homes from aircraft noise."

"Heathrow was also the first airport to sign the Paris Pledge for Action on climate change and continues to support the international aviation industry’s commitment to carbon-neutral growth from 2020 through carbon offsetting."

Although the Government has said the expansion can be delivered within "emissions limits", it has not decided what those limits are.

Rob Barnstone, campaign coordinator for Stop Heathrow Expansion has described the report as "damning" for both Heathrow and the Government.

He said: "It shows that for all their crowing about how Heathrow expansion can be delivered within air quality limits, carbon budgets and with range of mitigation measures on noise, the truth is, unsurprisingly, that it can’t.

"A third runway is proving more undeliverable by the week."

A Department for Transport spokesperson said:"We take our air quality commitments extremely seriously and have been very clear that the new runway will not get the go-ahead unless air quality requirements can be met.

"Our draft Airports National Policy Statement sets out a world-class package of compensation and mitigation measures to support local communities and limit the environmental impact of airport expansion.

"We are currently carrying out a full consultation, and want to hear everyone’s views."