New York's main contract, light sweet crude for delivery in September, fell 10 cents to 74.44 dollars per barrel in electronic deals before the official opening of the US market.

In London, Brent North Sea crude for September delivery lost 13 cents to 74.88 dollars per barrel in electronic trading.

Prices are winning support from "a combination of Nigeria's disruptions and the latest US inventory report which had quite a large drop in gasoline stocks and not much movement on the crude front", Global Insight analyst Simon Wardell said in London.

"And the market is reacting to the situation in the Middle East."

Wardell added there was an increasing realisation that Asian demand does not appear to be weakening.

"Chinese economic growth has been incredibly high in the second quarter," he said.

Tobin Gorey, commodities strategist at the Commonwealth Bank of Australia in Sydney, said the market was still feeling the ramifications after Royal Dutch Shell declared 'force majeure' on crude deliveries from Nigeria's Bonny oilfield for July and August. The move means contracts might not be honoured during those two months.

The Anglo-Dutch giant declared force majeure after a leak in an oil pipeline in southern Nigeria cut output by 180,000 barrels per day.

Separate disruptions blamed on unrest in the Niger Delta brought Nigeria's total production loss to 675,000 barrels per day, or 26 percent of the country's normal daily output, according to an industry source.

"It's not a short-term problem," Gorey said.