NEW YORK — Oil prices rose on Thursday, with Brent hitting six-month highs in part due to hopes of a Greek debt deal -- helping to offset a slight cut in OPEC's demand growth forecast.

New York's main contract, West Texas Intermediate (WTI) light sweet crude for delivery in March, jumped $1.13 to $99.84 a barrel.

Brent North Sea for March was up $1.39 at $118.59 in London, the highest level since August.

"Hopes of a new bail-out package for Greece, the weaker US dollar and the ongoing supply risks due to Iran, Sudan and Nigeria are giving buoyancy to oil prices," said Commerzbank analyst Carsten Fritsch.

"Additional support is provided by the frosty conditions in Europe which weather experts predict will continue until the end of the month," he added.

Greek leaders cobbled together a last minute deal on austerity cuts on Thursday, clearing the way for the eurozone to decide on a bailout package as unions called a new strike against the terms.

The announcement came just hours before eurozone finance ministers were due to meet on the accord and a debt rescue aiming to avert a Greek default and end a bitter chapter in the eurozone crisis.

Economic weakness in Europe and the United States and higher oil prices led OPEC on Thursday to cut its 2012 forecast for growth in global oil demand.

The Organization of Petroleum Exporting Countries now expects daily demand this year of 88.76 million barrels per day (bpd), down from its forecast a month ago of 88.90 million bpd.

Energy demand remains weak in the United States. The world's biggest oil consumer used on average 18.1 million barrels per day in the past four weeks, or 4.8 percent lower than the year-ago level, official data showed on Wednesday.