NICOSIA, CYPRUS, MARCH 2 -- Iraq said today that it had fired two missiles into Qom, a city regarded as holy by Iran's Shiite Moslems and a site not previously attacked with missiles.

Tehran Radio said Qom, about 75 miles southwest of Tehran, had been hit by one missile. It said there were no casualties. The broadcast said Iranian forces, in retaliation, fired three missiles at Baghdad, the Iraqi capital.

Qom is a center of religious learning in Iran and was home for decades to the Ayatollah Ruhollah Khomeini, Iran's leader. Because of the clergy's role in Iran's revolution in 1979, Qom is regarded by many as the place where the rebellion was spawned.

The city also houses the tomb of Fatima, daughter of the Prophet Mohammed, and is especially revered by Shiites, who constitute the vast majority of Iran's population.

As long as Iraq did not include Qom among its targets, Iran agreed not to attack four cities in Iraq -- Karbala, Najaf, Samarra and Kazimiyah -- that are holy to Shiites. Since the beginning of the war, in September 1980, Iran has sought to emphasize the differences between the Shiites, who are the majority in Iraq as in Iran, and the Sunni Moslems, who are the minority in Iraq but control the government there. The raid on Qom underlines the religious aspects of the conflict and appears to be aimed at intensifying the war.

The attack on Qom appears to be another step in a significant escalation in the so-called war of the cities, which has flared intermittently since 1985. Suspended for almost a year, it resumed Saturday when Iraqi warplanes attacked Tehran.

Iran's national news agency said Revolutionary Guards fired a ground-to-ground missile, believed to be a modified version of the Soviet Scud B type, at a government center in Baghdad today. The agency said Iraqi missiles fell on Tehran through the night, wounding 15 persons. In another attack, five persons were reported killed in a missile attack on a village near the northern city of Rasht. Since Monday, the Iraqis and Iranians have fired 26 missiles, Iraq accounting for 21 of them.

Iranian Prime Minister Mir Hossein Mousavi told Tehran radio that Iran would continue to respond to Iraqi attacks on civilian centers.

"Iraq will get tooth-smashing replies, both on its missile force and on its military forces at the fronts," Moussavi said.

Khomeini appeared in a 10-minute radio broadcast apparently aimed at calming fears in the capital over the rain of missiles.

"A mistake the westerners and our opponents make is that they think that Iranians are frightened by missiles," Khomeini said. "But they fired their missiles, killed people and what not, yet the Iranian people are sitting tight and laughing at them."

In an apparent reference to Soviet assistance to Iraqi President Saddam Hussein, the Iranian leader said, "Of course our people will not forget who helps Saddam in his mischiefs, who orders him and who gives him missiles."

The Iranian government protested to the Soviet Union yesterday, charging that Moscow had furnished Baghdad with the missiles that are hitting Tehran. Until now, Tehran, which is about 290 miles from the Iran-Iraq frontier, was beyond the range of Iraq's missiles.

Apparently Iraq has gone back to attacking civilian targets in the hope of persuading Iran to accept a United Nations cease-fire. Iraq has agreed to such a cease-fire, but Iran has refused.

Type: Surface-to-surface artillery missile

Length: 37 feet

Diameter: 33 inches

Warheads: Either nuclear or conventional high-explosive.

Range: About 110 to 190 miles

General: Part of the SS1 family of heavy artillery rockets produced by the Soviet Union. Scud transport vehicle also places the missiles upright for launch. Preparing for a launch takes about one hour.

Iran/Iraq: Iran uses Scud Bs to attack Baghdad, only 80 miles from its border. Western analysts say Iraq adds "strap-on" boosters to its missiles for the extra range required to reach Tehran, 290 miles from the border.

SOURCE: Jane's Weapons Systems, Associated Press