Stavros Dimas, the European environment commissioner, has said that the expansion of Heathrow airport will violate pollution limits imposed by the European Union (EU).
Furthermore, if the plans go ahead to build another runway, Mr Dimas has said he will take action against the airport.
The minister is not alone in his concern it seems, as local councils and Labour MPs have expressed similar disapproval to the plans.
Concerns were raised following a report from the Department for Transport (DFT) which illustrated that should the construction go ahead, it may not be viable to introduce pollution-capping measures.
Under the proposals, the DFT intends to use runways for both takeoff and landing simultaneously, which could see 60,000 more flights a year by 2015.
In related developments, five activists from the group Plane Stupid were up in court yesterday after unfurling anti-runway banners on the roof of the Houses of Parliament in protest against the runway last February.