Despite opposition from environmentalists and some Labour MPs, Prime Minister Keir Starmer is determined to deliver major infrastructure projects to grow a UK economy which has struggled to take off since the party came to power in July.

Following years of legal wrangling, Britain's Supreme Court ruled at the end of 2020 that Heathrow -- Europe's biggest airport by passenger numbers -- could build a third runway.

That overturned a legal decision to block construction on environmental grounds.

While the then Conservative government said building work could begin in 2022, the project has been delayed by further obstacles and upheaval created by the coronavirus pandemic.

Reeves was expected to deliver news of the government's Heathrow project alongside expansion plans for two other airports serving the capital -- Gatwick and Luton -- in a Wednesday speech focused on delivering growth thanks also to eased planning regulations.

The government has already approved upgrades to London's Stansted and City airports.

All but confirming the projects reported by British media, Chancellor of the Exchequer Reeves kept her cards close to her chest when telling the BBC on Sunday: "You'll see the plans when we set them out."

She argued that the project would result in less fuel wasted by aircraft waiting to land at the hub west of the capital's centre.

"A third runway will mean that instead of circling London, flights can land," Reeves said.

Energy Secretary Ed Miliband, who has previously opposed a third runway at Heathrow, this week insisted that a new airstrip must not impact the UK government's goal of reaching net zero carbon emissions by 2050.

- 'Increased pollution' -

But speaking on Tuesday, Greenpeace UK's chief scientist Doug Parr warned expansion at Heathrow would increase "noise, air pollution and climate emissions".

"Instead of picking up any old polluting project from the discard pile, the chancellor should focus on green industries that can attract investment and bring economic and social benefits for years to come," Parr said.

The comments came as Starmer and Reeves Tuesday met bosses from some of Britain's major companies -- including supermarket chain Tesco, Lloyds bank and defence group BAE Systems -- to reassure them on Labour's growth plans.

Britain's economy has stagnated in the almost seven months since the party ended 14 years of rule by the Conservatives in a landslide election victory.

Opposition lawmakers and some analysts have blamed the lack of growth on a decision by Reeves in her maiden budget to hike business tax.

Reeves will vow on Wednesday to go "further and faster" to kickstart the economy, according to extracts released ahead of her speech.

She will also unveil plans to deliver an Oxford-Cambridge Growth Corridor that will boost the UK economy by up to pound78 billion ($97 billion) by 2035 according to industry experts.

"Low growth is not our destiny. But growth will not come without a fight," she will stress.