There have been calls by oil-exporting countries at an energy conference in South Africa for more co-operation between producers inside and outside the OPEC cartel to restore and stabilise prices.

With prices currently languishing at near ten-year lows, the Saudi oil minister, Ali al-Naimi, urged the conference to take up the idea and eight countries -- including two from outside the Organisation of Petroleum Exporting Countries -- later met to discuss possible moves.

One participant was non-Opec Mexico, whose oil minister Luis Tellez had told the conference that agreements made earlier this year on limiting output had avoided a total breakdown in the oil market.

The deals are to be reviewed by OPEC in late November.