"We can convene (the committee meeting) at any time but under the plan, it gets together every two months," Novak said. He also confirmed that terms of the deal, which was agreed to be extended on Thursday, could in theory be changed at any meeting.

At Thursday's meeting in Vienna the Organization of the Petroleum Exporting Countries and some non-OPEC producers agreed to extend a pledge to cut around 1.8 million barrels per day (bpd) of output until the end of the first quarter of 2018. The initial agreement would have expired next month.

(Reporting by Olesya Astakhova; Writing by Katya Golubkova; Editing by Edmund Blair)