Ministers are “deliberately weakening” the green watchdog that will hold the government to account after Britain leaves the EU, according to Labour’s shadow Brexit minister.

Theresa May pledged last January to create a “world-leading, independent, statutory body” to ensure ministers stick to their commitments – replacing the power of the European commission to take governments to the European court of justice (ECJ) for not fulfilling their obligations.

Yet the UK watchdog will not have any powers relating to climate change, an issue of heightened public concern since the summer heatwave that has seen wildfires in the north of England and outbreaks of tropical diseases in parts of Europe.

Matthew Pennycook, Labour’s Brexit spokesman, said: “Our EU membership has been key to delivering and enforcing UK emission reductions. In choosing to exclude climate change from the remit of their environmental watchdog, ministers are deliberately weakening the tools we have to hold them to account. The Brexit process cannot be used as a cover to water down the UK’s leadership on climate change.”

The public deserves to have a watchdog with teeth that can enforce climate policy and ensure our pledges become reality Shane Tomlinson, E3G director

Greener UK, which represents 13 of the UK’s biggest environmental organisations including Friends of the Earth, Greenpeace, the RSPB and the National Trust , said it is very concerned about the omission of climate policy from the watchdog’s remit. About 55% of the UK’s planned carbon reductions are tied to regulations derived from the EU and would have been enforced by the European commission.

The watchdog should cover issues such as protecting harbour porpoises, ensuring that water quality and air quality remain high, and protecting wildlife habitats – issues that the European commission has taken action against the UK government.

Environmentalists believe the ECJ has been effective in getting Whitehall to live up to its pledges. According to research by the Institute for Government, between 2003 and 2016 the commission started 753 actions against the British government, of which about 120 related to the environment. Yet ministers were quick to settle matters before they reached the ECJ, which only passed judgments on 63 cases. However, 29 of those cases related to the environment, indicating that ministers would often not take action unless forced to do so.

In announcing its plans for the watchdog, the government argued that climate change was already covered by the Climate Change Act 2008, which created the committee on climate change and international treaties. But the CCC, which said recently that the UK would miss its 2025 and 2030 carbon reduction targets, only has powers to advise and report.

Its chairman, Lord Deben, told the environment secretary Michael Gove that excluding climate policy from the watchdog’s remit would be “artificial and potentially create problems”. But Gove is not responsible for government policy on climate change. The issue has now been passed over to the Department for Business, Energy and Industrial Strategy (BEIS).

Shane Tomlinson, director at E3G, part of Greener UK, said: “The government says it wants to be a leader in tackling climate change. However, leadership is not just about the promises you make, but being accountable for delivering on them.

“The UK public deserves to have a watchdog with teeth that can enforce climate policy and ensure that our pledges become reality.”

A spokesman for the BEIS said the government was committed to meeting its climate change targets.