U. S. crude oil futures pared gains in post-settlement trading on Tuesday, settling down at over $70 per barrel after industry data showed a surprise increase in domestic crude stocks last week.

The American Petroleum Institute, in a weekly inventory report, said that crude stocks rose 631,000 barrels in the week to Sept. 11, against the forecast in a poll of analysts for a 2.4-million-barrel drawdown.

The industry group said gasoline stocks rose 1.3 million barrels, more than twice the forecast for a 600,000 barrel build in the poll.

U. S. retail gasoline demand last week fell 3.1 percent from a year ago, but was nearly unchanged from the previous week, a MasterCard Spending Pulse report said.

The spread between the current front month and the five-year forward crude contract ended at $12.46, narrowing from $13.57 on Tuesday.

OPEC said that evidence of an impending world economic upturn appears to be gathering but recovery will be slow and gradual. OPEC left its world oil demand forecast for 2010 unchanged.

Crude oil is expected to trade slightly down early in the session as the build in crude inventory reported by API may pressurize the prices. This trend may reverse later in the session backed by optimism induced by strong economic data.