The North Sea’s biggest operator has swung from a near $1bn profit to an $8m (£6.3m) loss after the Government imposed its windfall tax and bosses cutback on investment.

Harbour Energy, which supplies about 15pc of the UK’s domestic oil and gas, said its half year results had also been hit by $16m of charges related to a review of its business triggered by the excess tax.

It hopes this will deliver €50m of savings from next year.

The business said that it had paid $437m (£344m) in tax during the six months, less than its tax bill for the first half of last year before the windfall tax on oil and gas companies was introduced.

It comes a day after rival operator Ithaca warned it is being forced to cancel projects and reduce production because of the “severe impact” of the Government’s windfall tax. 

Ithaca Energy, which is behind the controversial Cambo oil field, has told investors it is writing $74m (£58m) off the value of assets as a “direct impact” of the Energy Profits Levy. 

Harbour chief executive Linda Z Cook said: “We remain focused on maximising the value of our UK oil and gas portfolio, advancing our organic development projects and disciplined capital allocation.”

Andrew Keen of Edison Group said: “Harbour Energy has posted an anaemic set of results today, as January’s increase in the windfall tax on energy companies bites hard.”

Harbour Energy produced 196,000 barrels of oil equivalent per day during the first six months of the year.

However, it has narrowed its 2023 production guidance to 185,000 to 195,000 barrels amid delays and deferrals of drilling at partner-operated hubs, primarily at the Beryl oil field.

Total capital expenditure for the period was $400m, with the full year figure forcast to be $1bn, down from previous estimates of $1.1bn.

It said some expenditure plans had been shifted to next year after the delayed arrival of rigs, primarily at Andaman and the Greater Britannia Area, as well as the deferral of the subsea and platform drilling campaigns at Beryl.

The company expects to be net debt free by the first half of next year.