World oil prices floated to their highest level in 23 months today after remarks by major OPEC producers gave the market new assurances that output cuts would not be revoked before March 2000 at the earliest. London crude oil futures stormed to their highest level for two and a half years as the threat of an oilworkers' strike in key producer Venezuela deepened fears of a potential supply crunch. Benchmark Brent crude broke through a previous high of $21.75 and achieved a new peak of $21.88 a barrel, more than 50 cents up on the day and its highest level since February 1997.