Iran claimed Iraq used chemical weapons Tuesday for the second time in two months amid reports of heavy fighting on the northern front while Iraq sent missiles crashing into Iranian cities.

Iran said Iraq fired a Soviet-made missile Tuesday morning into the northwest Iran city of Tabriz, hitting a hospital for leprosy patients and killing and wounding many patients. Iraq launched the 180-mile missile strike on Tabriz at 8 a.m., a military spokesman in Baghdad said.Iraq sent a second missile crashing onto Tabriz homes several hours later, the Iraqi News Agency, monitored in Beirut, said.

Iraq also fired a missile into Tehran. Iran confirmed the strike on its capital but could not immediately provide accurate casualty figures.

Also Tuesday afternoon, an Iranian gunboat fired at a fully laden Saudi Arabian tanker setting it on fire, said Lloyd's of London, which insures several ships in the Persian Gulf region. There were no immediate reports of casualties.

Iran accused Iraq, its foe in the 7 1/2-year-old Persian Gulf war, of using chemical weapons in Iraqi Kurdistan in an effort to halt Iranian army advances after heavy fighting began Sunday night.

The accusation could not be independently confirmed. The use of chemical weapons by belligerents remains banned under the Geneva convention.

"Iraq dropped chemical bombs" the official Islamic Republic News Agency reported from Tehran. IRNA said the bombs were dropped early Tuesday "as (Iraqi) forces were losing ground to Iranian combatants on the northwestern fronts."

It said Iranian troops "immediately used protective devices, though many were injured."

The pro-Iranian Kurdistan Democratic Party of Iraq, or KDP, radio station earlier had claimed Iraqi planes dropped chemical bombs on Kurdish areas in Iraqi Kurdistan Sunday, killing "hundreds of civilians and wounding many others," the Iranian news agency said.

Iraq is accused of dropping chemical bombs on the Iraqi Kurdistan city of Halabja last month, killing 5,000 Kurdish civilians and injuring several thousand more.

Iran has said the Iraqi troops were injured by their own chemical bombs.