June 5 (Reuters) - Three British energy companies have

decided to delay by a year the planned start of oil production

at their joint-venture oilfield in the North Sea, citing the

need for clarity on the fiscal policies of the next government.

Jersey Oil and Gas ( JYOGF ), which owns 20% of the Buchan

field, gave the update on Wednesday on behalf of the joint

venture partners, among them Serica Energy ( SQZZF ) and

50%-stake-owning operator NEO Energy.

Shares in Jersey were down 16% and Serica's shares

dipped nearly 1% after the news.

Many North Sea oil and gas producers have been merging,

shifting overseas, and cutting investment as Britain's windfall

tax slashes profits and the opposition Labour Party threatens

more tax if it wins the next general election.

When Serica bought its 30% stake in the Buchan field from

Jersey Oil and Gas ( JYOGF ) in February, the target for first oil

production was in the fourth quarter of 2026.

That was before last month's call by British Prime Minister

Rishi Sunak for the general election on July 4. Jersey said on

Wednesday the first oil target has now moved to late 2027 after

the earlier-than-expected election date.

Jersey said the Buchan Field Development Plan was on course

for end-2024 approval.

But it added, "The exact timing for achieving this key

milestone and enabling project sanction is naturally linked to

securing fiscal clarity from the next government and ensuring

that the project remains financially attractive."

The Labour Party, with a strong lead in polls, has vowed to

raise the windfall tax by 3% to help fund its energy transition

strategy, which the North Sea oil industry has complained would

further deter investment.

"We anticipate the UK government will provide fiscal clarity

such that the operator of the Buchan redevelopment will have

sufficient confidence in the fiscal regime to progress with

project sanction," said WH Ireland analyst Brendan Long.

It is the best undeveloped oilfield of its kind in the UK

North Sea in terms of scale and low risk, he added.