"The IEA-reports make changes to their numbers creating uncertainty in the oil market," said one senior delegate. "This uncertainty makes a contribution to instability."

Opec insiders were particularly perturbed about last week's monthly IEA oil market report which revised down the outlook for global oil demand growth this year by 140,000 barrels a day to 1.5 million bpd. ``This does not help create a stable oil market,'' another Opec delegate said.

Oil fell about two dollars per barrel last week, partly, said traders, as a result of the IEA revisions.