OPEC and non-OPEC oil giant Russia agreed Thursday to extend production cuts until the end of 2018, following hours of discussions in Vienna.

The move was heavily telegraphed ahead of the decision, but the oil producers had earlier indicated they could exit the deal if they feel the market was overheating.

The deal to cut oil output by 1.8 million barrels a day was adopted last winter by the 14-member OPEC cartel, Russia and nine other global producers. The initial agreement was due to end in March 2018, having already been extended once.

Rather than extend the deal by nine months, the group said on Thursday it was implementing a new deal that will last from January to December of 2018.

The producers will review the deal at the next OPEC meeting in June to assess how it is impacting oil prices and global global crude stockpiles.

Additionally, Nigeria and Libya, two OPEC members exempt from the deal, have agreed not to increase their output next year above 2017 levels, according to the news agencies.

"To the market, we say there are no surprises to be expected from Libya and Nigeria," Saudi Energy Minister and current OPEC president Khalid al-Falih.

Falih exceeded expectations by securing Nigeria and Libya's cooperation, according to RBC Capital Markets' Global Head of Commodity Strategy Helima Croft.

"Throughout the year he earned a reputation as a tough compliance enforcer. Whether his successor, UAE's Suhail [Mazrouei], will be as stern on backsliders remains to be seen," she told CNBC, referring to the incoming OPEC president.

Earlier Thursday, Falih told CNBC that OPEC's consensus was "almost complete," before adding he did not anticipate an exit from the deal in the first six months of 2018.

The agreement does not include U.S. shale oil producers, and there are concerns that rising oil prices, largely thanks to the oil output cut, has allowed U.S. producers to come back online.

Ahead of the deal, however, Nigeria's oil minister had insisted the group was "aligned" and was in agreement about extending the cuts, despite the risk of a strong comeback by U.S. shale oil producers.