June 10 (Bloomberg) -- Presidential candidate John McCain said that while demand is the main reason for rising oil prices, speculators have contributed to the increase.

``There's a certain speculator effect here; how big that is is impossible for me to judge,'' McCain said in an interview on Bloomberg television today. ``There should be a thorough investigation.''

Crude oil for July delivery fell $2.95, or 2.2 percent, to $131.40 a barrel at the 2:30 p.m. close of floor trading on the New York Mercantile Exchange. Oil is heading for the biggest two- day drop in 11 weeks. Futures have more than doubled over the past year.

McCain also said the United States must lower its consumption of foreign oil.

``There's a finite supply of oil in the world that's controlled by cartels,'' McCain said. ``The lesson here is not so much to beat up on them, the lesson is to lower our dependence on foreign oil.''

The Arizona senator also endorsed development of alternative energy sources, especially nuclear power.

To contact the reporters on this story: Lorraine Woellert in Washington at lwoellert@bloomberg.net; Peter Cook in New York at pcook6@bloomberg.net.

Last Updated: June 10, 2008 15:08 EDT