At least 18 oil workers were killed when a drilling rig hit an oil platform in stormy weather, spilling gas and oil into the Gulf of Mexico, the state-owned oil company said. Seven workers were still missing.

Rescuers pulled 61 oil workers to safety from storm-tossed waters Wednesday but have yet to control the oil and gas leak, Mexico's oil monopoly Petroleos Mexicanos, or Pemex, said in a news release.

Eighty-one workers and five rescue personnel abandoned a subcontractor's drilling rig known as the Usumacinta on Tuesday, after it hit the Kab 101 light-production platform and damaged a valve amid 25-foot waves and winds gusting to 80 mph.

One survivor, Eder Ortega Flores, 25, told the Televisa television network that workers abandoned the rig and braved the raging seas only after leaking gas rose to unbearable levels and the supply of air from emergency breathing devices ran out.

"The personnel abandoned the platform, even though we know the conditions at sea were bad, but there was no other choice," Ortega Flores said. Once in the water, the waves battered the workers' orange-colored, covered life rafts.

"The life rafts didn't hold up under the force of the waves," he said. "They broke up, at least the one I was on, little by little, until the raft sank, and all my co-workers went into the sea."

He lost sight of them, and tread water through the night, until he saw the shoreline early Wednesday and swam to it.

The workers killed included four Pemex employees, seven employees of the subcontractor company that operated the rig, at least one rescue boat crew member, and six others who worked for other companies, the company said. One woman was among the dead.

The search continued for the seven missing workers. All those rescued were "out of danger," according to the statement.

President Felipe Calderon issued a statement expressing his "most sincere condolences and solidarity in this moment of pain" to the victims' families and offering them any help the government could provide.

Pemex said it would take three to five days to control the leak caused by Tuesday's accident, but noted that it mainly involved gas.

"The spill of crude oil into the sea has been less than originally thought," the company said.

It was unclear whether the missing workers were floating at sea or in life rafts. The Mexican navy sent eight helicopters and four boats to help in the rescue effort.

The Usumacinta, a mobile, self-raising drilling rig, was set up next to Kab 101, preparing to drill a well close to the platform. The force of the waves caused of the rig's "legs" to hit the valve assembly of the platform, causing it to leak oil and gas.

The mishap occurred about 20 miles offshore from the port of Dos Bocas in the Gulf coast state of Tabasco.

The storm forced Mexico's main oil ports to close. They remained closed Wednesday, Pemex said.

The Usumacinta drilling rig is owned by the Compania Perforadora Central SA de CV and operates under contract to Pemex.