September US Light crude on the after-hours NYMEX Access system edged a marginal one cent higher to $20.64 a barrel.

It had settled 69 cents higher at $20.63 in the New York Mercantile Exchange daytime trade on Friday.

North Sea Brent crude futures on the Singapore International Monetary Exchange (SIMEX) were unquoted. On Friday, the September Brent contract on London's International Petroleum Exchange (IPE) settled 68 cents stronger at $19.53.

September Brent on IPE had traded at a 20-month high of $19.55 before slipping slightly near the end of the trading day.

The boost to crude prices on Friday came as various producers sought to reassure the market that they would respect the output cut deal agreed earlier this year, due to last until April 1, 2000.

Funds returned to the market as buyers, encouraged by the prospect offurther price rises.

Mexico's energy minister Luis Tellez, the latest in a string of officials to assure the market of their commitment to the supply curb agreement, said on Friday that Mexico would not waver from its pledged output cut.

Earlier, Venezuela's oil minister, Ali Rodriguez, had said he saw no need to change the current production cut agreement at the Organisation of Petroleum Exporting Countries (OPEC) next meeting in September.

A joint statement along those same lines was also released on Thursday by the Libyan oil minister Abdullah el-Badri with visiting Venezuelan deputy oil minister Alvaro Silva.

Oil prices had slipped off their highs in the middle of last week on reports of high US crude stocks and comments by the president of Venezuela's state oil company that producers should agree to raise output if US crude prices rose above $22.