KUWAIT, JUNE 6 -- The State Security Court today sentenced six Kuwaiti Shiite Moslems to death for sabotage and subversion, the first such order against Kuwaiti citizens in more than three years of Iranian-inspired subversion here.

The decision ended a two-month trial of 16 men -- who diplomats said were of Iranian ancestry -- accused of trying to blow up oil installations and overthrow the state. It was seen as a potential watershed in relations between the ruling Sunni Moslem and minority Shiite communities here.

In addition to the death penalties, the court sentenced one man to life imprisonment and seven to lesser jail terms. Two men were acquitted.

The verdict was seen by western diplomats and Kuwaitis as confirmation of the deepening split between the Sunni and Shiite communities, caused largely by the nearly seven-year-old Iran-Iraq war.

The defendants, who are referred to in the official Iranian press as "holy warriors," were accused of causing explosions at oil facilities in June 1986 and just before last January's summit meeting here of the Islamic Conference.

Aged 19 to 36, the men were employed in the state-owned oil industry or the Education Ministry, indicating that they were solid middle-class members of Kuwait's welfare-state society.

Only foreigners were accused in a string of previous subversion cases, which started with attacks on the American and French embassies in 1983 and included an assassination attempt two years later against Kuwait's ruler, Sheik Jabir Ahmad Sabah.

The ruler, who has refused to carry out previous death sentences, is coming under increasing pressure to do so in this case to demonstrate the state's will to stop the series of sabotage attacks, according to Kuwaiti sources.

Outside the squat, four-story courthouse guarded by police in protective riot gear, about 200 men and women greeted today's verdict with shouts of "Death to America," "America is the number one enemy" and "We will not accept America in the gulf."

The slogans reflected opposition to the Kuwaiti government's plans to provide U.S. Navy protection against Iranian attack for half of its fleet by registering 11 tankers under the American flag.

The danger to Kuwait from the sabotage incidents was underlined by the most recent attack, on May 22. An explosion in a gas conduit was designed to blow up six storage tanks containing propane and butane at the Ahmadi refinery near here.

High-ranking oil industry officials said the chief saboteur -- a senior management supervisor named Faisal Karam Fairouz -- escaped abroad, although Tehran radio reported that he had been killed in the blast.

Officials said only luck and the perfect functioning of firefighting equipment prevented the explosion from spreading to the gas storage tanks. Each had a capacity of 450,000 barrels of propane and butane gas, the most inflammable of refined petroleum products.

Had they ignited, officials said, the explosion would have caused major destruction within a radius of up to three miles, devastating the refinery and Kuwait's third largest city, Fahaheel, home to 60,000.

"Had that propane gone up there would have been no need for the 'reflagging' deal," in which the United States is to defend Kuwaiti oil tankers, an oil official said, "since we wouldn't have had any oil industry left to protect."

Even before that incident, prominent Kuwaiti Shiites said as many as 200 Shiite staffers, a high proportion of them highly educated, had been removed from sensitive oil jobs. There were also unconfirmed allegations that Kuwaiti Shiites had been detained, placed under surveillance or had their passports confiscated.

In past years, the government, which includes only one Shiite minister, has weeded out Shiite officers from sensitive positions in the Army and the police.

Diplomats said the government became so sensitive to potential Shiite sabotage that only Sunnis were hired for the 4,000-man work force that built the complex to house last January's Islamic summit.

Sensing the trend, Sunni fundamentalists have launched a strident anti-Shiite campaign, especially in the press.

In turn, Kuwaiti Shiites tend to explain their coreligionists' involvement in sabotage as a response to Sunni discrimination and the government's tilt toward Iraq. "We don't ask {the government} to be pro-Iranian," in the gulf war, one Shiite intellectual said, "but they might have avoided a mess for us all by being neutral."

Such developments worry thoughtful members of both communities, for whom Lebanon remains a frequently discussed example that they hope Kuwait will avoid following. But a prominent Shiite intellectual remarked, "Even if the war ends tomorrow, the seeds of long-term instability have been implanted in our society."