NEW YORK, Feb. 1 (Xinhua) -- Oil prices extended gains on Thursday as a weaker U.S. dollar made the dollar-priced commodity more attractive for holders of other currencies.

The U.S. dollar decreased against most other major currencies on Thursday as investors digested a batch of economic data. The dollar index, which measures the greenback against six major peers, decreased 0.38 percent to 89.047 at 3:00 p.m. (2000 GMT).

Investor sentiment was also boosted by Goldman Sachs' outlook. Goldman Sachs said Thursday that the market has likely reached a balance between supply and demand, and forecast Brent crude to trade above 80 dollars a barrel later this year, according to Market Watch.

The West Texas Intermediate for March delivery increased 1.07 U.S. dollars to settle at 65.80 dollars a barrel on the New York Mercantile Exchange, while Brent crude for April delivery added 0.60 dollar to close at 69.65 dollars a barrel on the London ICE Futures Exchange.