Prosecutor General Ali Qodussi was quoted yesterday as saying that three Britons held in Iran since last August would be freed but a fourth would remain in jail.

Qodussi was speaking at a press conference for the local media shortly after a personal envoy of the archbishop of Canterbury said the three Anglicans missionaries had been transferred from prison to a government hostel pending their release.

Representatives of the foreign media were barred from the press conference but local reporters quoted Qodussi as saying investigations into the case of the three -- Drs. John and Audrey Coleman and Jean Waddell, former secretary to the Anglican bishop of Isfahan -- had been completed. They had been held in Tehran's Evin Prison along with businessman Andrew Pyke.

Documents relating to their case had been forged by a former agent of the shah's secret police, SAVAK, and three had been cleared, he was quoted as saying.

Meanwhile, the country's revolutionary leader, Ayatollah Ruhollah Khomeini, apparently alarmed over continuing political violence in Iran, told the police to use force if necessary to keep the peace.

The 80-year-old ayatollah addressed police officers at a Tehran mosque following a string of violent incidents that prompted gloomy warnings about the way Iran has gone two years after it Islamic revolution.