LONDON--Oil giant BP PLC (BP.LN) said Thursday it is selling its 36.22% interest in the Central Area Transmission System business in the U.K.'s North Sea to Antin Infrastructure Partners for 324 million pounds ($486 million).

Antin already has a 62.78% interest in the CATS business.

BP will get GBP302 million on completion, which is expected by the end of this year, and GBP22 million which is deferred, subject to certain post-closing adjustments, it said.

"The North Sea is an important region for BP. Our strategy here is to focus our resources and investment to create an efficient, sustainable and competitive business which will contribute to U.K. energy security for many years to come," Trevor Garlick, Regional President BP North Sea, said.

"Key elements of this are the completion of our major projects in the central North Sea and Shetland area, and continued management of our portfolio," he added.

BP is currently the operator of CATS. The other partners are ConocoPhillips (COP), with a 0.66% interest, and ENI S.p.A (E), with 0.34%.

Write to Ian Walker at ian.walker@wsj.com; @IanWalk40289749

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