Brent crude for August delivery was down 3 cents at $50.52 a barrel by 0650 GMT, not far from Monday's intraday high of $50.83, the strongest since November, Reuters reported.
NYMEX crude for July delivery was steady at $49.69 a barrel, after settling up $1.07 on Monday.
Crude futures have gained more than 85% from this year's lows following supply outages in Canada, Venezuela, Libya and Nigeria.
Nigeria's Bonny Light crude output is down by an estimated 170,000 barrels per day (bpd) following attacks on pipeline infrastructure, according to a source.
While OPEC failed to agree a clear oil-output strategy last week, traders said Saudi Arabia's promise not to flood the market has provided support to oil.
Oil was also propped up by a weak dollar, which wallowed near four-week lows against a basket of currencies. Federal Reserve Chair Janet Yellen said interest rate hikes are coming but gave little sense of when.
Read alsoStumbling dollar lifts oil prices, but uptick in U.S. drilling caps gains - ReutersU.S. commercial crude oil inventories likely fell by 3.5 million barrels last week, marking a third straight weekly drop, a preliminary Reuters poll showed ahead of the data by the American Petroleum Institute due out at 2030 GMT.
Traders were also awaiting China's trade data for May due out on Wednesday for fresh leads.
The market braced for signs of recovering U.S. oil production after weekly data from Baker Hughes showed that U.S. drillers added rigs for only the second time this year, analysts said.
