The government of Iran has designated Algeria as the country to take charge of Iran's embassy and its affairs of state here following the expulsion from this country of Iran's 35-member diplomatic corps, an Algerian embassy official said yesterday.

The spokesman said Algerian officials, along with some Iranian employes with nondiplomatic status, will move into the ornate building at 3005 Massachusetts Ave. NW. act as caretakers for the grounds and represent the estimated 300,000 Iranians now in the United States.

The request must be approved formally by the State Department, a department spokesman said yesterday.

"As a protective power, whoever is named will represent the interest of Iran in this country . . . take care of their property, be it upkeep or sale. The State Department has to approve, but won't be involved past that," the spokesman said.

Diplomatic sources, meanwhile, reported that Switzerland would monitor U.S. interest in Tehran.

The naming of Algeria as Iran's representative brought to a quiet close a tense three-day drama that began Monday when President Carter ordered all Iranian diplomats to be out of the country by midnight Tuesday.

Less than two hours before the deadline, 14 Iranian diplomats and their families boarded a British Airways jumbo jet at Dulles International Airport and flew to London.

Shortly afterwards, with police dogs straining at the leash and red lights from fire engines and bomb squad trucks blinking in the night, three teams of heavily armed District police, FBI agents and Secret Service technicians descended on the Iranian embassy.

The Iranian had gone, but sources said, police were told that several cases of guns, ammunition and explosives had been collected at the embassy since the overthrow of shah Mohammad Reza Pahlavi last year sources said police also had received reports that a group of Hanafi Muslims were hired to guard the embassy. The Hanafis and a lawyer for the Iranians said this report was not true.

All the doors in the embassy were unlocked and the technicians checked around doorways and baseboards for traces wires that might lead to bombs. But all they found was the calm interior of a once-ornate and lavish chancery that had been hastily vacated.

Police and special agents found some clothes, a pair of shoes, office furniture and some shredded paper, police sources said. One box that looked like it could have held a rifle was empty.

The Iranians appeared to have left quietly. Sources said much of the food had been given to countrymen who would be staying behind. Many belongings had been left, as well.

There were some signs that documents had been shredded and burned, but for the most part, the Iranians appeared to have been unprepared for their forced departure.

One Iranian official, sources said, sold his week-old car to a nearby embassy for about one-fourth of what he paid for it.

The sources said that FBI agents probably would return to the embassy later this week to take photographs of everything inside the building. The photos would be a record of the condition of the interior at the time of the closing, and could be used in the event of any claims of property theft or damage later.