U.S. crude fell slightly in volatile trade, reopening from Monday's U.S. markets closure for the Labor Day holiday to news of refinery outages.

The divergence between Brent and U.S. crude could grow if weekly crude inventories cited on Wednesday by industry group American Petroleum Institute (API) turn out to be higher than expected by the market.

Analysts polled by Reuters expect U.S. crude stockpiles to have risen by 200,000 barrels for the week ended Sept. 4.

API's weekly inventory report, usually due on Tuesdays, will be issued on Wednesday this time due to Monday's Labor Day holiday. The official report on weekly stockpiles, due on Wednesdays from the U.S. Energy Information Administration, will be delayed till Thursday.

Brent rose early on Tuesday as European equity markets took off on bullish second-quarter euro zone growth and stellar German exports data. Gains in Brent accelerated in New York after the European equities rally extended to Wall Street.

London-traded Brent settled up $1.89 at $49.52 a barrel, and was at $49.50 by 4:35 p.m. EDT (2135 GMT) in post-settlement trade. It fell $1.98 in the previous session.

Offsetting some of the bullish sentiment in Brent was China's mixed data on crude imports for August. The data showed a 6 percent gain year-on-year and 10 percent rise for the first eight months, but a 13 percent slide from July.

Also weighing on Brent was the growing potential for Iran to flood the oil market with more supply as the Obama administration gained further congressional support in its campaign to lift nuclear-related sanctions on Tehran crude exports.

U.S. crude settled down 11 cents, or almost a quarter percent, at $45.94, and was at $45.86 by 4:35 p.m. It had fallen almost $2 earlier in the session.

U.S. crude was weighed by the closure of the largest crude distillation unit at Exxon Mobil Corp's (>> Exxon Mobil Corporation) 502,500 barrel-per-day (bpd) Baton Rouge, Louisiana, refinery, on Sunday due to steam generation failure.

Valero Energy Corp (>> Valero Energy Corporation) was also shutting a 45,000-bpd hydrocracking unit at its 335,000-bpd refinery in Port Arthur, Texas, sources familiar with the plant's operations, said on Tuesday.

Phillips 66 (>> Phillips 66), meanwhile, has started shutting down the 182,000 bpd crude unit at its Wood River, Illinois refinery for planned maintenance ahead of its Sept. 11 schedule, sources familiar with the plant said. The shutdown, to last up to 35 days of planned work, comes after the unexpected closure of its 42,000 bpd fluid catalytic cracker due to a leak.

(Additional reporting by Lisa Barrington in London and Henning Gloystein in Singapore; Editing by Chris Reese and Lisa Shumaker)

By Barani Krishnan