Output cut at Buzzard oilfield for 4 days-trade source

LONDON, April 23 (Reuters) - Output has been cut at Buzzard, Britain's biggest North Sea oilfield, by about 50,000 barrels per day (bpd) for four days of maintenance, a trade source said on Wednesday.

The oilfield is the biggest contributor to the Forties crude stream, which is one of the four benchmark crudes underpinning the price of Brent.

Buzzard normally pumps at around 200,000 bpd and has been operating well in recent weeks.

But two Forties cargoes have just been deferred into May from April, and at least five cargoes have had their loading dates pushed back, with more deferrals expected.

Nexen (KSE: 005720.KS - news) , Buzzard's operator, was not immediately able to comment.

(Reporting by Claire Milhench; Editing by Elaine Hardcastle)