OPEC leader Saudi Arabia said on Monday, July 24 the group would quickly address weak compliance with output cuts by some OPEC states and would monitor rising production from Nigeria and Libya, which have been exempted from the curbs, Reuters reports.

OPEC has agreed with several non-OPEC producers led by Russia to cut oil output by a combined 1.8 million bpd from January 2017 until the end of March. But OPEC states Libya and Nigeria were exempted to help them recover from years of unrest.

The deal to curb output propelled crude prices above $58 a barrel in January but they have since slipped back to a $45 to $50 range as the effort to drain global inventories has taken longer than expected.

Rising output from U.S. shale producers has offset the impact of the output curbs, as has climbing production from Libya and Nigeria.

"We must acknowledge that the market has turned bearish with several key factors driving these sentiments," Saudi Energy Minister Khalid al-Falih told a meeting of a committee that monitors the deal between OPEC and non-OPEC states.

Alongside Saudi Arabia, the committee known as the JMMC includes Russia, Kuwait, Venezuela, Algeria and Oman. It has the power to recommend measures to other producers involved in the pact, depending on market conditions.