Harbour Energy - the UK's biggest oil and gas producer - is reported to be selling its stakes in a number of major North Sea fields.

The move, which has been reported by Reuters this morning, comes as the Labour government prepares to bankroll renewable energy products by raising and extending the duration of taxes on oil and gas revenue.

The Budget, set to be formally announced on next Wednesday, is expected to include plans to rise in the Energy Profits Levy, commonly known as the windfall tax, as well as an extending it.

It is feared the move will trigger key players in the industry to pull out of the region and instead look to invest in assets overseas.

According to Reuters, Harbour Energy has launched a sale process of its stakes in the Armada, Everest, Lomond, Catcher and Tolmount fields as it seeks to reduce its exposure in the North Sea.

In a deal completed last month, the Harbour purchased Wintershall Dea's non-Russian portfolio for $11billion as it looks to diversify outside the North Sea, more than doubling its production in the process.

Harbour Energy did not comment on the sale process, insisting it was focused on the Wintershall Dea integration.

The government is also lining up new environmental guidance, for oil and gas projects, which executives predicted could further deter investments in the ageing basin, where output has dropped by around 75% since its peak in the late 1990s.

Last month the boss of the North Sea's biggest oil and gas producer questioned the timing of Labour's changes to the Energy Profits levy (EPL).

Linda Cook, the CEO of Harbour Energy, said the "hurdle to attract investment" in the UK was now going to be higher, after Labour announced that the EPL would rise from an overall rate of 75% to 78%, run until 2030 rather than 2029, and that it would remove allowances to allow companies to offset investment spending against their tax bill.

The company felt the brunt of the windfall tax when it was initially introduced in 2022, cutting 350 onshore jobs in the UK.

Ms Cook told the Financial Times: "Everyone understands that the UK will need oil and gas for many years to come, so why don’t we seem to want to use our own?"

KeyFacts Energy: Harbour Energy UK country profile