The international airport here remained closed today for the fourth consecutive day as rebellious Moslem Druze virtually held Lebanon's travelers hostage to political demands.

Druze leader Walid Jumblatt said in a published interview today that his militiamen would not allow the airport to reopen in the "foreseeable future" unless Lebanese authorities acceded to his demand that the Cabinet resign and talks commence to give the Druze more power in the government.

"We've got nothing to lose from now on," Jumblatt said in an interview in Beirut's leftist As Safir newspaper, "and let each party shoulder his responsibility."

However, spokesmen here for Jumblatt indicated more flexibility on the airport issue.

As the crisis of authority intensified, the government of President Amin Gemayel announced plans for a "national reconciliation" conference bringing together the leaders and warlords of the various factions, whose disgruntlement continues after eight years of civil strife.

There was broad condemnation earlier this week when Jumblatt's militiamen kidnaped three government ministers and held them overnight at his ancestral palace in the mountains south of here.

But the Druze offensive against the government and its fledgling Army appeared to raise latent anxieties that threaten to rip apart the fragile consensus for the government in the capital. Virtually all of the rest of Lebanon is under the control of occupying Syrian and Israeli forces or various militia.

A conservative Moslem leader of Beirut, former prime minister Saeb Salam, who has been one of Gemayel's staunchest supporters, warned yesterday that the support Gemayel had when elected last fall "now appears to be waning away." Salem told a television interviewer, "This is why I find myself constantly alerting the administration to the many mistakes that have been committed by the various agencies."

American diplomats are known also to have urged the Christian-dominated government to reach out more to the Moslem communities. The indications are that Gemayel and his advisers in recent weeks have grown more antagonistic to the American advice.

The underlying issues are the same as they were at the outbreak of the 1975-76 civil war--revision of a system of government in which authority is disproportionately assigned to Maronite Christians.

Gemayel's government has indicated a willingness to consider change but has insisted that this come after foreign occupying forces leave. Jumblatt, who has struck an alliance with Syria and is in a strong bargaining position now, has insisted on immediate revisions in the system. One of his demands has been that a second legislative chamber be created, with a Druze as its leader. The leadership of the current single chamber is reserved for a Shiite Moslem.

The troubles this week broke out after the Lebanese government sent in reinforcements to an Army outpost separating Druze and Christian villages in the mountains south of here.

The mountains, scene of on-again, off-again sectarian fighting since last August, have been under the overall control of occupying Israeli forces. The government has made plans to deploy Lebanese Army soldiers throughout the mountains when the Israelis carry out their announced pullback to southern Lebanon.

Jumblatt, fearing that soldiers will side with Christian militia against the Druze, has insisted on a political agreement before the Army deployment. Apparently believing that the Army was going ahead with its plans, Jumblatt's militiamen launched an attack on Army positions, shelled the airport and U.S. Marine positions around it and directed artillery to areas near the Defense Ministry and presidential palace.

Travelers formed long lines at the port today to take boats to Cyprus. Jumblatt's spokesmen had indicated yesterday that the airport could reopen today. But a statement today indicated authorities must promise not to use it for military purposes. The statement claimed that military aircraft were taking off to strike at Druze positions.

Jumblatt in an interview with CBS Saturday warned U.S. Marines to stay away from Lebanese Army positions at Beirut airport, which he said his forces will continue to bombard. "I'm just giving the small advice to the U.S. Marines to stay away from the Lebanese Army positions. It's better for them and better for me," he said.

Jumblatt, who has been in self-imposed exile since last fall after an assassination attempt, reportedly met yesterday with Jordan's King Hussein in Amman, then went to Saudi Arabia, where he met today with King Fahd.