OPEC's top two producers agreed Thursday to strengthen their commitment to production cuts, as the oil cartel reported a collective increase in output last month in a setback for its deal to pump less.

The pledge from Saudi Arabia and Iraq, the first and second largest OPEC producers, came after their oil ministers met in the Red Sea city of Jeddah.

Saudi Energy Minister Khalid al-Falih and his Iraqi counterpart Jabbar al-Luaybi also vowed to ensure coordination of their nations' oil policies, according to the Saudi Press Agency, as the Arab neighbours seek to upgrade strategic ties.

OPEC states and other oil producers agreed in November to cut output until March 2018, in its long-haul gambit to erode a world oil glut and boost prices. 

But despite the commitment, crude production by OPEC members saw an uptick in July, including by Saudi Arabia which had championed efforts by the cartel and allied independent producers to extend an output freeze.

Output from the 14 cartel members hit 32.87 million barrels per day (mbd) last month, OPEC said in its monthly report on the oil market, up from 32.69 mbd in June.

The inability of some members to cut ouput has raised doubts about OPEC's capacity to enforce the November deal.

Saudi Arabia and Iraq have suffered huge economic pain because of sliding oil prices.

Luaybi's visit symbolises a growing rapprochement between Riyadh and Baghdad as the kingdom seeks to increase its influence in Iraqi politics and undercut the say of regional rival Iran.

The minister also met with Saudi Crown Prince Mohammed bin Salman in Jeddah to discuss "joint opportunities in the economic fields and energy in particular", SPA reported.