Oil prices extended gains on Monday as a weaker dollar and easing worries over Britain's possible exit from the European Union helped buy back the commodity after six straight days of declines.

London Brent crude for August delivery was up 29 cents at $49.46 a barrel by 2238 GMT on Sunday, after settling up $1.98, or 4.2 percent, at $49.17 on Friday.

NYMEX crude for July delivery, which expires on Tuesday, was up 31 cents at $48.29 a barrel, after closing up $1.77, or 3.8 percent, on Friday.

Campaigning for Britain's vote on EU membership resumed on Sunday after a three-day hiatus prompted by the killing of a pro-EU lawmaker. Three opinion polls ahead of Thursday's vote showed the "remain" camp recovering some momentum, although the overall picture remained one of an evenly split electorate.

Oil storage tanks Crude oil storage tanks in Cushing, Oklahoma, March 24, 2016. Photo: REUTERS/NICK OXFORD

The pound was last up against the dollar at $1.4450 from $1.4350 on Friday. The Japanese yen held not far from its highest level against the dollar in almost two years.

Oil prices continued to recover despite data showing U.S. energy firms adding oil rigs for a third week in a row, suggesting higher production to come. Oil services firm Baker Hughes reported nine rig additions in the week to June 17.

Sizzling home price rises in China's biggest cities showed signs of easing in May, but sharp gains appeared to be spreading to smaller cities, making policymakers' job harder as they look to support the faltering economy without inflating bubbles.

France's hard-line CGT union ended a strike on Friday that had paralyzed traffic for 26 days at the Fos Lavera oil terminals on the Mediterranean, the country's biggest oil hub, a management official at port operator Fluxel said.