MEXICO CITY - U.S. Homeland Security Secretary Michael Chertoff said Friday that U.S. intelligence helped Mexico capture a cocaine-laden smuggling submarine this week.

As the Mexican navy finished hauling the 33-foot vessel to shore, Chertoff disclosed that the U.S. government had shared information with Mexican authorities before Wednesday's operation.

"We shared information with the Mexican navy, but the Mexican navy acted alone in actually executing the seizures: their marines, their helicopters, their naval vessels," Chertoff told reporters here after meetings with Mexican officials on security issues.

He did not specify what type of information U.S. officials had passed along before Mexican commandos seized the vessel and its four-member Colombian crew.

While the homemade vessels are being used increasingly by Colombian drug suppliers as a way to evade radar detection, it was the first time one was captured off the coast of Mexico.

Mexican military officials said after getting the seized vessel to shore Friday that it contained about 6 tons of cocaine.