Sir Keir Starmer has “full confidence” in the Transport Secretary despite having disowned her criticism of P&O Ferries amid concerns it would jeopardise a £1 billion investment in the UK, Downing Street has said.

Number 10 on Monday sought to draw a line under the Cabinet rift that saw Louise Haigh describe the firm as a “cowboy operator”, saying the Prime Minister “absolutely” backs the minister after the fallout.

In an official press release last week, Ms Haigh attacked the firm for its decision in 2022 to sack 800 workers and employ agency staff on lower pay, which it insisted was necessary to stave off bankruptcy.

In a subsequent ITV interview, she said she had been boycotting P&O for years “and I encourage consumers to do the same” – remarks which Sir Keir later said were “not the view of the Government”.

The criticism triggered a row with P&O’s Dubai-based parent company DP World in the run-up to a major UK business summit, with ministers scrambling over the weekend to salvage a key investment for the London Gateway container port.

Asked by reporters if the Transport Secretary had the Prime Minister’s full confidence, Sir Keir’s official spokesman said on Monday: “Yes, absolutely. The Transport Secretary in the run-up to the summit delivered significant investment in electric buses.

“She’s put an end to industrial disruption seen for the past two-and-a-half years that has cost the economy and commuters dearly, and she’s been driving forward reform and bringing rail services back into public ownership.”

Earlier on Monday, DP World confirmed it would go ahead with its £1 billion backing after what the company described as “constructive and positive discussions” with the Government over the weekend.

It said the investment plan would expand London Gateway to become Britain’s largest container port within five years, increasing capacity by building two new shipping berths.

A second rail terminal would also be added to the site to deal with increased container trade.

The expansion would create a further 400 permanent new jobs, the company said.

Sultan Ahmed bin Sulayem, group chairman and chief executive of DP World, said: “DP World London Gateway will help make Britain’s trade flow in the future by connecting domestic exporters with global markets and delivering vital supply chain resilience for the whole economy.

“I am proud of this major investment which underlines DP World’s long-term commitment to the UK.”