Naval frogmen Saturday rescued 45 members of a 52-man crew from a U.S.-built Peruvian submarine that collided with a Japanese tuna boat and sank 110 feet in the Pacific. The bodies of four crewmen were recovered and three others were missing and presumed dead.

The World War II era submarine, the Pacocha, sank Friday night 4 miles west of the seaport of El Callao near Lima after the tuna boat rammed into its stern at about 6:50 p.m., the navy said.President Alan Garcia, speaking more than 24 hours after the collision, said the bodies of the submarine's captain and three crewmen were recovered and three other crew members were missing and presumed dead in the submarine's flooded compartments.

"As a result of rescue operations, 45 survivors have been recovered," a naval statement said. "The survivors are under care at the Naval Medical Center under observation."

Garcia, speaking at a news conference in the presidential palace, said the survivors were treated in hyperbaric chambers to prevent illness from decompression.

Garcia called the captain of the Pacocha, Daniel Nieva Rodriguez, "a hero" and said "the crew members, marines and officers have earned our respect today."

The Japanese fishing vessel, Kyowa Maru, carried an estimated 20 crew members, including some Peruvians, authorities said. None were injured, Japanese Embassy spokesman Masayoshi Ono said.

Garcia said experts believed the Japanese boat may have mistaken the cruising submarine for a smaller boat when the two vessels collided at the entrance to the harbor in El Callao.

On Saturday, rescuers used a diving bell that attached to the hatch of the submarine and began bringing crew members to the surface from the submarine.

The bell, linked to the surface ship by a cable, was bringing crew members up two at a time, Castro said.

Callao, Peru's largest port, is eight miles west of Lima. Port traffic was banned until Monday to facilitate rescue operations, the port authority said Saturday.

A U.S. Embassy spokesman who declined to be named said the U.S. Navy was sending a special team and equipment aboard three C-141 transport planes to assist in the rescue operations.

The U.S. equipment includes a diving bell designed for submarine rescues, the official said. The Peru navy did not describe the diving bell already used in the rescue.

The Peru navy said the submarine was purchased in 1974 from the U.S. government. The vessel, formerly the U.S.S. Atule, was commissioned on June, 21, 1944, according to Jane's Fighting Ships.