OPEC oil output rose in May, the first monthly increase this year, a Reuters survey found on Wednesday, as higher supply from two OPEC states exempt from a production-cutting deal, Nigeria and Libya, offset improved compliance with the accord by others.

The Organization of the Petroleum Exporting Countries pledged to reduce output by about 1.2 million barrels per day (bpd) for six months from Jan. 1 as part of a deal with Russia and other non-members. To provide additional support for prices, the producers decided at a meeting last week to prolong the deal until March 2018. They discussed whether to include Nigeria in the output cap but decided against it for now, OPEC delegates said.

Nigeria and Libya were exempted because their output has been curbed by conflict. However, supplies from both nations staged a partial recovery in May, lifting overall OPEC output by 250,000 bpd to 32.22 million bpd. The biggest increase came from Nigeria specifically, where the Forcados production stream began loading cargoes for export. The Forcados pipeline had been mostly shut since it was bombed by militants in February 2016.