On Friday, Egyptian time, OPEC ministers agreed to reduce production by 1 million barrels a day from 1 January.
The immediate reaction to OPEC's decision was a slide in the international crude oil market, with futures settling below $US41 a barrel, their lowest in almost five months and about $US15 a barrel less than the all-time record set in October.
Two-thirds of the world’s oil is produced outside the OPEC bloc and many energy analysts are sceptical that OPEC will be able to enforce production cuts on some of its member states. Many speculate output would continue at levels not much lower than current rates of production.