Speculation in the world financial market has played an important role in skyrocketing oil prices, among other factors such as supply woes and a weak dollar, analysts said.

New York's main oil futures, light sweet crude for July delivery, jumped 10.75 dollars a barrel to close at a record 138.54 US dollars per barrel on Friday.

In the day's trading, the benchmark contract crossed the 137, 138 and 139-dollar-per-barrel (dbp) thresholds for the first time and soared to an all-time high of 139.12 dbp.

The strong surge sharply reversed the nearly 14-dollar drop over the previous two weeks and caused fresh fears of dire consequences as a result of runaway fuel prices.

Speculation amid the weakening US dollar and concession fears in the aftermath of the US sub-prime mortgage crisis were clearly one of the vital players behind the skyrocketing oil prices, observers said.

Officials of the Organization of Petroleum Exporting Countries (OPEC), which pumps 40 percent of the world's oil, have repeatedly pointed to speculation as the main cause of rising oil prices.

OPEC Secretary-General Abdullah al-Badri said on May 23 the cartel could do nothing to curb the hike in oil prices as speculation and the weak US dollar, rather than insufficient output, should be held responsible.

"When we see there is a shortage of supply, we will act," he said. But in the present situation, "even if we increase output tomorrow, the prices will not come down because of speculation and because of a weak dollar."

The fluctuation of crude oil prices is closely related to the global financial market, a Chinese official said on Saturday at the energy ministers' meeting among India, China, the United States, Japan and South Korea in Aomori, Japan.

Rising oil prices should be put into the context of the global financial market, which could be affected by a wide range of factors such as the change of exchange rates, geopolitics, political instability and natural disasters, said Zhang Guobao, vice chairman of China's National Development and Reform Commission.