France accepted a claim of diplomatic immunity yesterday for three Iraqi Embassy staff members arrested for firing on French police and a Palestinian terrorist who had just surrendered following a siege at the embassy Monday.

The decision was seen as a movie to avoid strains in relations with Baghdad, France's second largest oil supplier and a reported customer for its Mirage fighter jets. The Foreign Ministry made the French position clear after discussions yesterday morning with Iraqi Ambassador Mundhir Tawfik Wandawi.

After the decision was made known, several hundred French policemen, shouting "scandal" and "shame" gathered at the medieval-style Paris police headquarters. They said they would complain by letter to President Valery Giscard d'Estaing if the three were released.

At one point, 100 police cars, lights flashing and horns blaring , drove double-file to the Interior Ministry to protest the government's decision to allow the Iraqis to return home.

A police union official said that several officers would remain at headquarters during the protest to insure that the three Iraqis remained in detention.

The Foreign Ministry decision clears the way for the three, who denied shooting at police, to return quickly to Iraq. They were identified as two secretaries and an attache, all on the Iraqi diplomatic register. French Foreign Ministry officials said.

One French policeman and one Iraqi Embassy guard were killed, and the terrorist and three others were wounded in the shootout. French police blamed the shootings on the "incomprehensible" behavior of what they said Monday night were Iraqi Embassy guards.

Baghdad was reportedly embarrassed by the shootout and Iraqi newspapers published only brief accounts yesterday morning, according to reports in the French press.

The Iraqi ambassador had issued a statement late Monday night claiming the shootout was touched off by "friends" of the terrorist brought to the scene by a second terrorist who escaped early in the siege.

The Iraquis' claim that they did not fire on police and the ambassador's account contradicted French police reports that the three tried to kill the terrorist after he laid down his arms and was being led away by French police.

The terrorist, said to be a Palestinian about 25 years old, claimed to be Ahmed Hammami, the brother of a Palestine Liberation Organization representative assassinated in London last January, police said.

French police said they had not yet made a positive identification of the wounded terrorist or the terrorist who escaped in the initial minutes of the siege.