Brent futures dipped 4 cents to $48.31 after closing down 37 cents in the previous session, with both contracts finishing with modest losses for a fourth straight session

US commercial crude stocks likely fell by around 2.5 million barrels to 538.8 million in the week ended 20 May, a preliminary Reuters analysts' poll taken ahead of weekly industry and official inventory data showed on Monday.

Gasoline stocks likely fell 1.3 million barrels last week, while distillate inventories, which include heating oil and diesel fuel, likely decreased by a million barrels, the poll showed.

The American Petroleum Institute is due to release its inventory data later on Tuesday, while the US Department of Energy's Energy Information Administration is due on Wednesday.

The dollar index rose marginally higher against a basket of currencies on Tuesday, as investors continued to factor in an increased chance of a near-term US interest rate rise.

A stronger greenback makes dollar-priced commodities more expensive for holders of other currencies.

Still, US data economic overnight was disappointing, with the preliminary Markit manufacturing PMI in May falling to 50.5, the lowest level this year.

"Markit PMI data continued to point to a difficult period for manufacturing as Q2 unfolds," ANZ said in a market report on Tuesday.

Crude exports from Iraq's southern oil fields have fallen by more than 200,000 barrels per day to around 3.15 million barrels so far in May, according to an industry source and loading data. That followed the previous month's near-record of 3.36 million bpd.

Libya's crude production has risen above 300,000 barrels per day after the reopening of the Marsa al Hariga export terminal in the east of the country late last week, a spokesman for the Tripoli-based National Oil Corporation (NOC) said on Monday.