The US pharmaceutical group behind the Mounjaro weight-loss drug has said it will unpause its UK investments if ministers agree to regularly increase NHS drug prices and end a rebate scheme.

Patrik Jonsson, the president of Eli Lilly’s international business, said the company was in talks with UK ministers and that he was optimistic about reaching an agreement this summer for Britain to pay more for its medicines.

He said in an interview with the Financial Times that the talks would also explore “innovative” pricing plans, such as linking payments for anti-obesity drugs to whether the treatment will help patients return to work.

It comes as the US pharmaceutical industry ramps up pressure on the UK, with Keir Starmer agreeing last year to the first increase in NHS cost effectiveness thresholds in 27 years. This raised the price the NHS will pay on potentially life-extending drugs, from £20,000 to £30,000 a year for every year of life gained to £25,000 to £35,000.

Eli Lilly was one of several pharmaceutical companies to ditch or pause almost £25bn in planned investments in the UK last year. The drug developer paused its plans to invest in a laboratory site in central London.

Jonsson told the FT that the resumption of Eli Lilly’s investment would depend on the outcome of its talks with the government.

“What we would need to see is actually those goals turning into really a well-defined action plan with interventions and timelines,” he said.

He added that prices for medicines in the UK had been “far too low for far too long, and even with the current threshold, we are not back to where we started more than 20 years ago”.

He said: “The threshold can’t be written in stone for another three decades.”

After pressure from Donald Trump on international drug pricing, the UK agreed to pay 25% more for new medicines by 2035 as part of a US-UK drug pricing deal. The funds will come out of the NHS budget instead of the Treasury’s and could eventually reach £9bn a year, campaigners have said.

Large pharmaceutical companies have also protested about a “rebate” scheme, under which they are required to pay back a chunk of revenue from sales of branded medicines, if the amount the public health service uses is higher than an agreed rate.

This is expected to fall in 2026, although Jonsson said payments “should actually get down to zero” over time.

He added that while the NHS had rationed access to the Mounjaro injection, the company was “very eager to look into more innovative agreements”. It is expected to launch a pill version of the weight-loss drug later this year.

“We have seen some data already [on] how intervening and treating obesity actually reduces absenteeism … for an employer, that makes a heck of a difference,” he said. “We have 2.8 million of the UK eligible working population that aren’t coming to work out of sickness. I think there are real opportunities to discuss new models, to work together, and that includes outcome-based agreement.”

A spokesperson for the Department of Health and Social Care said: “Everyone deserves access to the best and most innovative treatments, and our changes to medicine pricing will make sure thousands of NHS patients gain faster access to new treatments.

“We remain fully committed to delivering the UK-US pharmaceutical agreement, including the changes to the Nice cost-effectiveness threshold.”