Oil slips further below $57

Oil slipped further below $57 barrel on Monday as a stronger dollar and ample US supplies outweighed Opec output curbs and rising tensions between the United States and Iran.

The dollar fell 0.3 percent versus a basket of currencies. US energy companies added oil rigs for a 13th week in 14, data showed on Friday, and US crude inventories rose by more than expected last week.

Brent crude was trading at $56.56 a barrel by 1402 GMT, down 25 cents, having touched an intra-day high of $57.13. U.S. crude was down 13 cents at $53.70.

"It's most likely the stronger US dollar," said Commerzbank analyst Carsten Fritsch of the reason for the dip in oil. A stronger dollar makes crude more expensive for other currency holders and usually weighs on the oil market.