Robin Walker will be responsible for environment matters in the new Department for Exiting the European Union (DEEU).

The MP for Worcester told the House of Commons Environmental Audit Committee that he had volunteered for the role because ‘it is something that is hugely important we get right’.

Walker was giving evidence to the committee alongside Defra minister Thérèse Coffey as part of its investigation into the possible effects of Brexit on environment policy and legislation.

He said the aim of the DEEU in relation to the environment was to build on what had been established by the UK’s membership of the bloc and to maintain the country’s role as a world leader on environmental protection. ‘It’s important we continue on the course, which I think the UK was on before it joined the EU, of being one of the leading countries when it comes to environmental legislation.’

Coffey, MP for Suffolk Coastal, said the government would meet its general election manifesto pledge to leave the environment in a better state than it found it: ‘I wouldn’t want anyone to be under the illusion that, just because we are leaving the EU, that has changed our environmental ambitions.’ Defra would publish soon its 25-year plan to to improve the state of the UK’s natural environment, she promised.

The two ministers also said that the government would engage fully in developing EU environment policy until the UK leaves. ‘While we are part of the EU we will play a full and active role. We are not stepping away from the table,’ said Coffey. Walker reported that engagement with other member states on developing policy was continuing.

Responding to a question from committee chair and Labour MP Mary Creagh on why the environment was not considered a separate matter in the new department, Walker said it was a cross-cutting issue that affected a number of policy areas, such as ‘market access’ and ‘trade and partnerships’.

According to Walker, a number of Defra officials had been seconded to DEEU to help the department to support the prime minister in negotiating the UK’s exit.

Creagh asked Coffey whether Defra, which is facing budget cuts of 15% over the next few years and had already lost 900 employees, had enough resources to both work on Brexit and deliver its departmental responsibilities. ‘I am led to believe we have the right balance,’ Coffey said.

The Defra minister declined to give an assurance that the UK would maintain EU air quality standards after Brexit, saying that the government was taking action to set up clean air zones in five UK cities to reduce pollution and comply with existing rules. ‘Our air quality is better than it has been – that doesn’t mean it is the best in the world but we will continue to strive to develop it, but a lot of that has to be driven locally,’ she said.