Investing.com - Oil was up over 1% Tuesday as the dollar slumped and on expectations of compliance with output cuts.
Brent crude was up 73 cents, or 1.31%, at $56.59 at 08:30 ET. U.S. crude rose 78 cents, or 1.49%, to $53.15.
Saudi Arabia Monday reaffirmed its commitment to reining in its output.
However, doubts remain about other producers, while eyes are also on a possible increase in activity by North American shale drillers.
OPEC and non-OPEC producers have agreed to cut output by some 1.8 million barrels a day in the first half of this year.
Saudi Energy Minister Khalid al-Falih Monday expressed confidence in compliance with the agreed cuts.
The dollar index fell well below the 101 mark. A weaker dollar supports demand for oil.