NEW YORK, Dec. 29 (Xinhua) -- Oil prices rose on the final trading day of the year, with U.S. oil prices closing above 60 U.S. dollars, amid an unexpected fall in American output.

Oil prices posted solid gains on Friday, as analysts said a decline in U.S. production and commercial crude inventories lifted sentiment.

On the economic front, the number of rigs operating in U.S. oil fields remained unchanged at 747 rigs this week, while gas rigs are down 2 rigs at 182, according to oilfield service firm Baker Hughes' weekly report released Friday.

Meanwhile, a weak dollar also supported the oil markets on Friday. The dollar index, which measures the greenback against six major peers, was down 0.44 percent at 92.195 in late trading.

The West Texas Intermediate for February delivery increased 0.58 U.S. dollar to settle at 60.42 dollars a barrel on the New York Mercantile Exchange, while Brent crude for February delivery ticked up 0.15 dollar to close at 66.87 dollars a barrel on the London ICE Futures Exchange.