By Olesya Astakhova, Ahmad Ghaddar and Alex Lawler

LONDON/MOSCOW (Reuters) - A meeting of eight top ministers of OPEC+ will likely keep oil output policy that calls for gradual oil output hikes from April unchanged, two OPEC+ sources said on Thursday.

The talks began shortly after 0900 GMT, one of the sources said. Another source said the ministers would likely stress the need for stronger adherence to oil output targets.

Record Kazakhstan output has angered several other members of the group, including top producer Saudi Arabia, sources have told Reuters. OPEC+ is urging the Central Asian country, among other members, to make further cuts to compensate for excess production.

Eight members of OPEC+, a group that includes the Organization of the Petroleum Exporting Countries and allies led by Russia, are scheduled to raise oil output by 135,000 barrels per day in May.

The group is expected to proceed with this plan, both sources on Thursday said, following similar comments on Tuesday and Wednesday from other OPEC+ delegates.

The May hike is the next increment of a plan agreed by Russia, Saudi Arabia, UAE, Kuwait, Iraq, Algeria, Kazakhstan and Oman to gradually unwind their most recent output cut of 2.2 million bpd, which came into effect this month.

OPEC+ also has 3.65 million bpd of other output cuts in place until the end of next year to support the market.