TOKYO (Reuters) - Goldman Sachs has cut its price forecast for Brent and West Texas Intermediate by US$15 a barrel for the first quarter of 2015 because rising production in non-OPEC countries outside North America is expected to outstrip demand.

The U.S. investment bank slashed its forecast for WTI to US$75 a barrel from US$90 and for Brent to US$85 a barrel from US$100, it said in a research note on Sunday. The bank's analysts expect WTI to fall to as low as US$70 a barrel and Brent to US$80 a barrel during the second quarter of next year, when it expects oversupply to be the most pronounced.

U.S. crude futures edged up on Monday to hold above US$81 a barrel, following a four-week slide that has pulled prices down by nearly 10 per cent amid abundant supply amid and weak demand.

NYMEX crude for December delivery was up 4 cents at US$81.05 a barrel by 0104 GMT, after settling down US$1.08 on Friday following a spike up on Thursday on news that Saudi Arabia had boosted production but cut supplies to the market in September.

London Brent crude for December delivery was down 19 cents at US$85.94 a barrel, after settling down 70 cents.