Oil futures climbed more than $1 a barrel on Monday, after Saudi Arabia raised its prices for crude sales to Asia for the second month running, signalling improved demand in the region.

International benchmark Brent regained ground after tumbling as much as five per cent on Thursday, when a preliminary nuclear deal was finally reached between world powers and Iran.

More Iranian oil could enter global markets if that is followed by a comprehensive deal by June. But expectations of an immediate increase in supply have been tempered as analysts warned a ramp-up in exports could take months and would likely not happen before 2016.

"While clearly a bearish headline, a final deal and full lifting of sanctions still faces a number of obstacles," Morgan Stanley analysts said in a note. "Even if a final deal is reached, we do not expect any physical market impact before 2016," the analysts said.

Brent crude for May delivery touched a high of $56.90 a barrel and was up $1.50 from Thursday at $56.45 by 5.48 a.m. EDT. U.S. crude for May delivery was $1.49 higher at $50.63 a barrel, after earlier touching $50.97.

There was no settlement in either Brent or U.S. crude futures on Friday as markets were closed for the start of the Easter holiday. Despite the sanctions on Iran, China's imports from the OPEC producer are set to rise from August as a Chinese state trader has signed a deal with the National Iranian Oil Company to buy more condensate.

The world's top exporter Saudi Arabia kept output steady and cut its official selling prices (OSPs) sharply late last year in a fight for market share during a global supply glut. Its ability to raise prices for April and May suggests its strategy is working, although competition has kept its flagship Arab Light at a discount to Oman/Dubai quotes, analysts said.

"There is still competition for the Asia market even though it is also a sign that some of the production elsewhere is less able to compete in the market right now," said Shunling Yap, a senior oil and gas analyst at BMI Research. Concerns over fighting in Yemen also supported prices, as fighting between a Saudi-backed coalition and Shi'ite Houthi forces continued in the port city of Aden, which overlooks a major shipping lane between Europe and the Arab Gulf.

On the supply front, the number of rigs drilling for oil in the United States declined by 11 last week to 802, the smallest drop since December, a weekly survey by oil service firm Baker Hughes showed on Thursday.