Oil prices fell to nearly $66 in electronic trading Wednesday after traders collected gains from a recent rally, although analysts said the market continued to be supported by supply concerns in Iran and Nigeria.

OPEC President Edmund Daukoru answers questions during a news conference at the African Oil and Gas and Finance conference in Algiers March 4, 2006. [Reuters]

Light, sweet crude for May delivery fell 17 cents to $66.06 a barrel in electronic trading on the New York Mercantile Exchange. Gasoline futures rose 1.15 cent to $1.9070 a gallon, while heating oil prices rose fractionally to $1.8570 a gallon. Natural gas fell 4.2 cents to $7.023 per 1,000 cubic feet.

Last week, prices made solid gains on supply concerns linked to U.S. gasoline inventories, which have been falling ahead of the U.S. summer, when demand peaks.

The uncertain outlook for supplies out of Iran and Nigeria was bolstering oil prices, analysts said.

The U.N. Security Council voted unanimously last week to demand that Iran suspend nuclear enrichment but Iran has remained defiant, saying its enrichment plans are "irreversible." The standoff has escalated tensions over Iran's nuclear program.

Iran said Monday it successfully tested its second new torpedo in as many days, the latest weapon to be unveiled during war games in the Gulf that the military said are aimed at preparing the country's defenses against the United States.

Also of concern to the market is Nigeria, where about 27 percent of output has been knocked out by ethnic rebel attacks in the Niger Delta region. Militants have pledged more attacks aiming to get locals a bigger cut of the oil revenues held by the federal government. The country usually produces 2.4 million barrels a day.

Nigeria is the fifth-largest exporter of crude to the United States.