* Yemen operations shut due to labor dispute
* Buzzard output halved till cooling system repaired
* Nexen shares down 2.7 pct in Toronto (Adds details, comment; updates shares)
CALGARY, Alberta, May 9 (Reuters) - Nexen Inc NXY.TO, Canada's No. 6 independent oil producer, said on Monday it halted production at its Yemen operations because of a labor disruption and warned that output from its Buzzard field in the North Sea was down by half due to equipment problems.
The operating woes pushed the company's shares down 64 Canadian cents, or 2.7 percent, to close at C$23.14 on the Toronto Stock Exchange.
Nexen suspended production Sunday night at its Masila and Block 51 fields in Yemen -- which produce about 70,000 barrels of oil per day in total -- because of labor action by unionized workers at the fields.
"The union said they would reduce the number of people who would be available and therefore we did not feel we could operate," said Pierre Alvarez, a spokesman for the company. "So we went into shutdown last night."
Last Wednesday, workers on the company's Hadramout oilfield went on a brief strike. They agreed to remain on the job for five days while talks continued toward a settlement, a union spokesman said. [ID:nLDE7431NK]
Nexen, which also operates in Canada and the Gulf of Mexico, said it is currently operating at reduced rates at its Buzzard field in Britain's North Sea due to problems with the the cooling system on the field's platform.
Alvarez said output from the field is likely to be about half the normal rate of around 200,000 barrels per day for a few months until repairs can be completed.
Buzzard is a major contributor to the Forties oil stream, which usually sets the dated Brent crude oil benchmark used in Europe, Asia and the Middle East to price cargoes.
Nexen has a 43.2 percent stake in the Buzzard field. Suncor Energy Inc (SU.TO) owns 29.9 percent while BG Group BG.L holds 21.7 percent and Edinburgh Oil & Gas Plc holds the remaining interest.
About half of Nexen's oil production comes from its North Sea holdings while Yemen accounts for about 12.4 percent, according to Reuters data. (Reporting by Scott Haggett and Amruta Sabnis; editing by Rob Wilson)