Armed FBI agents and Coast Guardsmen raided a Liberian-registered oil tanker off the coast of Rehoboth Beach, Del., late Tuesday, arresting 24 crew members who had threatened to kill the ship's captain and release 290,000 barrels of oil into the ocean unless the ship's Greek owners paid them union-scale wages.

The unprecedented raid, which occurred in international waters at the request of the Liberian government, followed 29 days of hostility between the captain and crew that the Coast Guard said ended in a mutiny.

On May 25, after the tanker Ypapanti was refused entry into the port of Philadelphia because it lacked proper safety equipment, the crew took the captain and 11 of the ship's officers hostage. The chief officer jumped overboard June 8 and was rescued by the Coast Guard.

While the ship was resting in international waters 17 miles from the Rehoboth shore, U.S. officials could do nothing about the growing tensions except monitor radio communications from the ship.

In the past few days, the Coast Guard had overheard increasingly frequent threats from the crew against the officers' lives and their plans to release the oily cargo into the ocean and to ignite the tanker.

The 24 mutinous Pakistani and Indian crewmen were removed from the tanker yesterday in handcuffs and taken to the Coast Guard station in Cape May, N.J., where they were turned over to federal immigration agents, who said the crew members would be held in a Brooklyn detention center until they were sent back to their home countries.

The mutiny was suppressed in 30 seconds, faster than the heavily armed members of the Coast Guard and an FBI team had expected, said Armand Chateau, captain of the Coast Guard cutter that led the assault. Chateau said he ordered the raid after a spokesman for the angry crewmen told him, "They would rather die than work for those wages."

Chateau said that Coast Guard officers surprised the rebels by sneaking aboard as food from the Coast Guard vessel was being loaded on the tanker. The crewmen surrendered to the agents without firing a shot.

Eleven crewmen who did not participate in the takeover stayed with the ship, which is heading for the Bahamas.

The tanker, which set sail from Nigeria, was scheduled to deliver its oil to the Atlantic Richfield Company's refinery near Fort Mifflin dock in the Philadelphia River. The100,000-ton ship is owned by the Greek shipping firm Astrolabe Bay Shipping Corp., which is based in London.

In Philadelphia, the tanker was denied entry into all U.S. ports because it did not meet newly enacted federal maritime regulations. The rules require oil tankers to have special equipment to prevent accidental explosions and oil spills when oil is pumped out.

The FBI and Coast Guard were asked to board the tanker after four weeks of negotiations between the crew and the ship's owners disintegrated. According to Coast Guard officials, the crewmen, some of whom said they had not been paid in nine months, were demanding that their wages be raised to match the pay of North European seamen as called for by the International Transport Workers Federation.

In addition, the crewmen were demanding plane tickets to their home countries and back pay of $225,000 in U.S. currency. Coast Guard officials said the crew was predominantly Pakistani and Indian, while the ship's officers and captain are Greek.

Many private shipowners register their vessels in Liberia or under other so-called "flags of convenience" with lenient shipping regulations. These ships often draw their crews from poor Third World countries such as Pakistan where a seaman will work for low wages--often as low as $276 a month--under often uncomfortable conditions.

The London-based federation has been campaigning for a minimum wage of $703 a month for theseseamen. Last year, some British dockworkers and tugboat operators boycotted the "flag-of-convenience" ships until the crews received union-recommended wages.

Coast Guard officials said the militant crewmen from the Ypapanti initially said they would speak only with a union official when they began their siege. They gave the name of a Philadelphia lawyer, Walter Z. Steinman, who reportedly did some work for the federation.

George B. Cooper, Liberia's deputy commissioner for maritime affairs attached to the Liberian Embassy here, said the crew's demands amounted to "blackmail."

"The whole purpose of that union is to destroy flag-of-convenience shipping," said Cooper, who began negotiating with the crewmen two days after they seized control of the ship. "Once they have a dispute on board they think they can blackmail the owners into giving more money. The problem was not that they were not being paid. They just wanted more money."

Cooper said he arrived at the vessel on May 27, along with attorneys representing the ship's Greek owners. But those negotiations failed, he said, when the crewmen refused to accept his offer of back pay and transit home.

The Philadelphia attorney, Steinman, also tried and failed to get the crewmen to accept their contract wages and transit home, Cooper said. "He came back frustrated," Cooper said. Steinman returned to Philadelphia and refused to work for the crewmen further, Cooper added. Steinman could not be reached for comment.

"After we exhausted all efforts to mediate and conciliate, we asked the U.S. government to step in," Cooper said. He said that he telephoned the Liberian foreign ministry in Monrovia, which in turn contacted the Liberian ambassador here, who made the official request for American intervention to the State Department. American assistance in such cases is provided for in treaties with Liberia regarding marine pollution.

A State Department spokesman, who asked not to be named, said, "In view of the Liberian government's ability to resolve the situation and the deteriorating conditions on board the vessel, we offered our good offices in trying to assist in solving the matter.

"There was an apparent lack of trust between the owners and the crew," the spokesman said. "I think it is rather an unusual situation."