The United States yesterday ordered the closing of the Libyan diplomatic mission in Washington and gave all Libyan diplomats five working days to get out of the country because of what the State Department called "Libyan provocations and misconduct, including support for international terrorism."

The dramatic action against a country that supplies approximately 640,000 barrels of oil a day to the United States -- about 10 percent of total imports -- and in which some 2,000 Americans, mostly oil company employes, live, stops and one step short of a full break in diplomatic relations.

In announcing the decision, State Department spokesman Dean Fischer said that "from the first days of the administration" both President Reagan and Secretary of State Alexander M. Haig Jr. "have made known their very real concern" about Libyan government misconduct.

Fischer added: "We have also been concerned by a general pattern of unacceptable conduct by the [Libyan] People's Bureau in Washington which is contrary to internationally accepted standareds of behavior." The Libyan government of Col. Muammar Qaddafi refers to its embassies in many countries as "People's Bureaus."

Fischer, under questioning by reporters, declined to provide specific details about what Libyan actions here or abroad provoked the ouster.

The United States has taken action before against Libyan diplomts here, ousting four of them in May 1980 for their alleged participation in a campaign of intimidation against exiled opponents of Qaddafi living in this country. The British expelled four Libyan diplomats that same month.

These actions followed the murders of eight Libyan dissidents in England, Italy and Greece. The Libyans deny involvement in the deaths, but western governments believe they are traceable to Qaddafi's stated campaign of "physical and final liquidation of the opponents of popular authority . . . at home and abroad."

In October, a Libyan dissident student in Colorado was shot and wounded; FBI officials say they believe that attack also was linked to the alleged Libyan campaign.

Sources here said this case and indications that People's Bureau members in the United States, were involved in tracking down dissident exiles were factors in the decision to oust all the Libyan diplomats.

The Reagan administration has made a fight against interntional terrorism, which it has linked primarily with Moscow and Cuba, a cornerstone of its foreign policy.

Aside from the charges of involvement in terrorism, the administration has been annoyed by Libyan military intervention in Chad in northern Africa, by Qaddafi's promotion of a revolutionary pan-Islamic empire of Saharan states, by the mercurial Libyan leader's increasingly close relationship with Moscow and a $12 billion stockpile of Soviet arms bought by Qaddafi.

Fischer and White House assistant press secretary Mort Allin said they saw no reason why the expulsion order should affect the oil relationship between the two countries.

The United States spends about $12 billion a year for Libyan oil, which is of a type especially important to refineries on the East Coast. Allin maintained, however, that "the U.S. response to Libyan policies will not be determined by that relationship."

The chief of the Libyan mission here, Ali Ahmed Houderi, was informed of the expulsion order after being called to a State Department meeting with Undersecretary Walter J. Stoessel.

Houderi told reporters later that the order would be complied with, but that the Libyans were being made "scapegoats." An attorney for the People's Bureau, Richard Shadyac, called the U.S. move "a preposterous action," and said the Libyans have "denied the rebulous allegations of terrorism which have come out of the State Department," United Press International reported.

Houderi said, "We are not reactionary. We do not export revolution. The only thing we seek is freindship. We came here to build bridges between our people and yours . . . and the only thing we regret is not finishing the job," the Associated Press reported.

Fischer did not say how many members the People's Bureau had here, but Hourderi told The Washington Post on Tuesday that there were about 60 to 75 people connected with the mission here, including 25 on the embassy staff and their families.

There are 4,000 Libyan students in the United States, Fisher said. They will be allowed to remain if they obey the law and keep up their academic programs.

The U.S. Embassy in Tripoli was sacked and burned in December, 1979, by pro-Iranian mobs. The embassy has been closed officially since last May, when the last U.S. diplomats were withdrawn.

Fischer said Libyan authorities have "repeatedly refused our numerous requests" to use a third country to represent U.S. interests in Libya.

Fischer said the United States would allow Libya to set up an interest section in another embassy here if the United States is accorded similar privileges in Tripoli.

Since December, 1979, the State Department has issued a number of advisories to U.S. firms in Libya to reduce their staffs there. Yesterday, a new one accompanied the expulsion order.

"Due to unsettled relations" between the two governments, it said, "the Department of State warns American citizens against any travel or, or residence in, Libya. Travelers should also be informed that the U.S. Embassy in Tripoli is closed and the U.S. government is not in the position to provide consular protection and assistance to Americans presently in Libya."