The five hijackers of a Kuwaiti airliner warned today that they were ready to kill three Kuwaiti diplomats and another American official unless Kuwait met their demands to release a group of convicted terrorists.

In a statement relayed to the control tower at Tehran Airport and then distributed by the Iranian news agency, the hijackers said there were others aboard the Kuwaiti Airways Airbus, "including Americans and Kuwaitis, whom we will not free and their fate is also liable to be death unless the Kuwaiti government comes to its senses and frees our enchained brothers."

"We are not responsible for anyone who will be killed since we have previously given our warnings and set a deadline," they said.

It was not clear whether they had established a new deadline or were referring to an earlier threat to blow up the airliner if their demands were not met.

The hijackers gave the names of the three Kuwaiti diplomats and identified the American as Charles Kipper, who they said was "worthy of execution" because his "cooperation with the Central Intelligence Agency was very clear."

The three Kuwaitis were identified as Ibrahim Mohanna, described here as Kuwait's consul general-designate in Karachi; Khalifa Hussein Muslim, a former ambassador to Sudan and now director of the Foreign Ministry's archives, and Mahmoud Abdul Ranhim Andi, a former prosecutor and head of the Foreign Ministry's inspectorate general.

After another day-long session of the Kuwaiti Cabinet, there was no sign tonight that Kuwait was ready to give in to the hijackers' demands. No official statement was issued after the meeting, which ended at 10 p.m. local time, but sources here said the Kuwaiti government was still adamant in its refusal to comply.

The hijackers have been calling for the release of 17 persons convicted in a spate of bombings here, including two at the U.S. and French embassies last Dec. 12.

Three of the 17 were condemned to death last March and are awaiting execution, while the others were sentenced to prison terms ranging from life imprisonment to five years.

Twelve of the convicted terrorists are Iraqi nationals, three are Lebanese, one is Kuwaiti and one stateless.

The Kuwaiti Cabinet also held an all-day meeting yesterday without reacting to the hijackers' demands. The government has called a special session of parliament Saturday to discuss the crisis, during which the public mood may become clearer.

The country has been on a three-day holiday, celebrating the birthday of the prophet Mohammed. Because of this, little has been said so far about the hijacking by any Kuwaiti officials or politicians.

In their statement today, the hijackers identified the two Americans they have already shot as Charles Freud and William Stanford. The State Department said that Charles Floyd Hegna of Sterling, Va., and William L. Stanford of Alexandria, Va., were members of a U.S. Agency for International Development auditing team. There was no State Department confirmation of the name "Charles Kipper" used by the hijackers for the third American threatened with death.

The hijackers' statement also referred to another American passenger whose name, as broadcast by Tehran radio, sounded like "Stanley Stevers." A State Department spokesman told The Associated Press that there was no American named Stanley Stevers aboard the plane.

There have been conflicting reports on the number of passengers shot by the hijackers since they seized the Kuwaiti airliner Tuesday on a flight from Kuwait to Karachi via the Persian Gulf port of Dubai in the United Arab Emirates. But it now appears that four passengers, including the two Americans, have been killed. This, at least, is the number the hijackers referred to in their statements today.

Two American women were released earlier and the two other Americans, whom the hijackers called Kipper and Stevers, remained hostages on the aircraft.

The hijackers released eight more passengers today, six Pakistanis and two Iranians, in return for the agreement of Tehran authorities to publish their statement and relay their demands to the Kuwaiti government. The Iranian news agency IRNA said tonight that a total of 107 passengers had now been released and that 57 persons remained on board. But a French news agency report put the number of persons still being held hostage at 49, including eight crew members.

The hijackers are also demanding that their statement be published in the Kuwaiti media in return for the release of more of the remaining hostages, most of whom are believed to be Pakistanis. The statement, as published by the Iranian news agency, appeared to be mostly a denunciation of Kuwait, which it accused of torturing the 17 convicted terrorists under "the joint butchering machine of Kuwait, the U.S. and France to extract false confessions from them."

"We will not make the slightest retreat from our positions . . . The American masters of Kuwait will see how blood will become victorious over their shaky rule," the statement said.

"Our hope is that the fate of our enchained mujaheddin holy fighters brothers in Kuwait and all over the world would meet God's approbation . . . with hopes of martyrdom, praise be to God, the cherisher and sustainer of the world," it ended.

Washington Post special correspondent Nora Boustany reported the following from Beirut:

The hijackers are believed to be linked to the Iraqi underground organization Al Dawa which has close links with Iran. The prisoners convicted in Kuwait have been identified in an official Kuwaiti report as members of the Al Dawa Moslem fundamentalist group.

Last January, an underground faction calling itself the "Islamic Action Organization" warned the Kuwaiti government against doing any harm to the prisoners, threatening to blow up Kuwaiti properties in the Persian Gulf and abroad. The "Islamic Action Organization" is believed to be linked to Al Dawa.

Sources in Beirut were skeptical of reports that the hijackers were members of the radical Shiite Moslem group called Hezballah or "the party of God."

Another shadowy group calling itself Islamic Jihad, which claimed responsibility for the Kuwait bombings last December, called foreign news agency offices urging the hijackers to leave Tehran. The anonymous caller denied that Islamic Jihad was involved in the hijacking but said, "We support it."

One theory circulating in Beirut was that the hijackers may be part of the team that carried out the Kuwait bombings last December. In addition to the 17 convicted terrorists held in Kuwaiti jails, four others were convicted but are at large. Intelligence sources in Beirut were speculating that these four may be among the hijackers.