LONDON (Reuters) – Oil prices fell on Monday as the first tropical storm of the Atlantic season looked set to steer clear of oil infrastructure in the U.S. Gulf Coast.

U.S. light, sweet crude for July delivery was 93 cents lower at $70.70 by 1540 GMT.

Brent crude (LCOc1) fell by $1.20 to $69.28 a barrel.

On Sunday, Alberto became the first named tropical storm of the U.S. hurricane season, rekindling memories of the devastation wrought last year by Rita and Katrina.

The U.S. National Hurricane Center on Monday issued a hurricane warning for Florida's Gulf Coast.

But most analysts and forecasters predicted Alberto would spare refineries and oil platforms in the U.S. Gulf of Mexico, source of about 25 percent of U.S. oil and natural gas. "I don't think it's really that much of a concern right now," said John Brady, a broker at ABN AMRO in New York. "All it does is tell us we really are in hurricane season."

About 15 percent of production is still shut in in the U.S. Gulf following last year's violent hurricanes.

Devon Energy Corp., on Sunday evacuated workers from a platform because of Alberto and Anadarko Petroleum Corp said on Monday it had suspended some drilling.

However, it predicted operations were likely to return to normal by Tuesday.

Iran, Iraq

Prices on Friday had risen by more than a dollar on fears about instability in oil producer Iraq and possible disruption of Iranian supplies.

Iran initially had appeared favorable to a package of proposals from Western powers aimed at persuading it to halt nuclear enrichment.

But a U.N. watchdog said on Thursday Iran had launched a fresh round of nuclear enrichment and Iran's government said on Monday it would not negotiate over its right to enrich uranium.

Tehran restated its position just before the International Atomic Energy Agency's governing board began meeting in Vienna.

It was expected to debate Iran, but not to pass any resolutions.

In Iraq, al Qaeda vowed to carry out further attacks following the killing last week of its leader in the country Abu Musab al-Zarqawi.

"We plan large-scale operations that will shake the enemy and rob them of sleep, in coordination with the other factions of the Mujahideen Council," an Internet statement said.

Further price support came from news imports of crude oil by China -- the world's second biggest oil consumer -- had leapt by 19 percent in May compared with a year earlier, according to customs data.