Kwasi Kwarteng said he is happy to “engage” with a call to cut fuel duty as MPs sought a steer from the Chancellor on a wide range of tax and spend questions.

Following his first significant set of fiscal announcements in the Commons as Chancellor, Conservative backbenchers looked to test Mr Kwarteng’s instincts and draw his attention to a number of policy issues, including aid spending, business rates, and Sunday opening hours.

Conservative MP Robert Halfon, a long-time campaigner for lowering fuel duty, said petrol and diesel prices have been at “historic highs”.

He asked the Chancellor if at the next budget he could “please do everything he can to cut fuel duty”.

Mr Kwarteng replied: “I’d be very happy to engage my right honourable friend on that.”

Pressed on when the UK’s aid spending would return to 0.7%, Mr Kwarteng did not commit to a clear timescale.

Tory former international development secretary Andrew Mitchell told the Commons: “Can I remind him of the importance of the UK investment in tackling international problems, whether it’s pandemics, illegal migration or climate change?

“That’s about British expertise but also it’s about British money. Can he confirm to the House we are on track to restore what was a manifesto promise of bringing back the 0.7% in 2024?”

Mr Kwarteng replied: “We’re always looking at our manifesto commitments and given our leadership in this I hope we can come to the 0.7% as is practicable and the public finances allow.”

Conservative MP Nickie Aiken (Cities of London and Westminster) sought the Chancellor’s attention to consider reforming the “punitive” business rates system.

Mr Kwarteng said the Government is looking at a “tax review to fit our tax system to the 21st century”.

While Conservative former minister Matt Warman urged the Chancellor to look at “deregulating Sunday opening hours” so businesses on the high street can better compete with the ones on the internet.

“This is a deregulating Government. I wonder if the Chancellor would look at deregulating Sunday opening hours so that we can compete on the high street just as we can compete on the internet,” Mr Warman said.

Mr Kwarteng replied: “We have looked at this in the past. It was not without controversy, but I’d be very happy to hear his ideas in this on this subject.”

Responding to a question from Conservative former health minister Dan Poulter, Mr Kwarteng said he is happy to have a “discussion” about the annual and lifetime pension allowances.