Oil output from the UK's largest oilfield has risen to more than 200,000 barrels per day (bpd), trade sources said on Thursday, boosting supply of the North Sea crude that normally sets the dated Brent benchmark.

Supply from Nexen's Buzzard field, usually the largest contributor to the North Sea's Forties crude stream, has recovered after a technical problem that cut output, the sources said.

There was a problem but it has come back a lot quicker than expected, said one of the sources, an equity holder in Forties output. It's over 200,000 barrels per day today.

It was not clear when production was reduced. Oil traders on Monday said there was a production problem at the field. Nexen spokesman Pierre Alvarez confirmed on Thursday that output had returned to normal levels.

The Forties crude stream is important for the wider oil market as it usually sets the value of dated Brent, which is used to price up to 70 percent of the world's physical oil and is part of the underlying market for Brent crude futures.

Shipments of Forties have been subject to an unusual level of delays and cancellations since May due mainly to production problems at Buzzard, supporting prices.

Output from Buzzard was stable during October, reducing the number of delayed cargoes. But trading sources said on Wednesday, following the talk of lower Buzzard output, that two more November-loading cargoes had been deferred.

This brings the number of delayed November shipments to five, according to a Reuters tally. The November programme originally listed 22 cargoes.

Buzzard is the largest of the oilfields feeding the BP Plc- operated Forties pipeline in the North Sea, and normally contributes about a third of the total Forties output.

Nexen said when reporting earnings on October 27 that output at the field, where it has been commissioning a fourth platform, would vary.

(Reporting by Alex Lawler; Editing by Alison Birrane)