For the second time this week, a top-of-the-line Iraqi jet fighter was shot down after the American military said it violated the cease-fire by flying.

Air Force officials Friday said the pilot of a second plane - a propeller-driven Iraqi trainer that accompanied the Soviet-build Su-22 fighter - ejected from his plane after an American F-15 shot down the jet, causing the trainer apparently to crash as well."This is the second violation of the cease-fire this week," said Maj. Thomas Nickerson, a spokesman for the military's Central Command, noting Iraq has been told repeatedly not to fly its fixed-wing military aircraft.

But Air Force officials said the Iraqis, facing a full-scale Kurdish rebellion in northern Iraq, seem desperate enough to consolidate their remaining jets in Baghdad that they're willing to gamble on daylight flights.

In cease-fire meetings with their American counterparts, Iraq has requested permission to fly their jets because they claim they need to take them to repair depots for routine maintenance. But the Americans have refused on grounds this would add to Iraq's combat capabilities.

Friday's shootdown was the second time this week that F-15 fighters have downed an Su-22, known in the West by its NATO code name Fitter.

The earlier incident occurred Wednesday over Tikrit - Saddam Hussein's home town. Friday's shootdown, which occurred at 11:40 a.m. local time, took place over the northern Iraqi town of Kirkuk, the military said.

- Iraqi rebels, meanwhile, reported sporadic clashes with government forces in Baghdad Friday, the Muslim sabbath, amid growing anger over the alleged arrest of the elderly patriarch of the Shiite branch of Islam.

The opposition also reported fierce battles north of Najaf, the Shiites' holiest city, where Imam Ali, the founder of the sect, is buried.

Iran's official Tehran Radio, in an unsourced report, said rioting against Saddam has spread to Baghdad. Tehran Radio said earlier that Saddam had ordered a state of emergency in the capital.

- Kurdish sources said Jalal Talabani, leader of the Patriotic Union of Kurdistan, and his aides were on their way to northern Iraq by road from Syria.

The Kurds claimed they captured Kirkuk, Iraq's northern oil center, on Wednesday and that most of the mountain region has been purged of government forces. They said they would continue to push south to link up with the Shiites, whose rebellion apparently has been less successful.

Bayan Jabr, a spokesman for the Supreme Assembly of the Islamic Revolution of Iraq, reiterated allegations that Grand Ayatollah Abul-Kassem al-Khoei, the Shiite patriarch, had been arrested in Najaf.

Speaking in Damascus, Jabr said helicopter-borne commandos "savagely attacked" the school of theology in Najaf on Tuesday, battled with the rebels, then arrested Khoei, his son and a number of aides. He said Khoei was flown to Baghdad and forced to meet with Saddam Hussein.

Khoei has not returned to Najaf, and his whereabouts after the March 19 meeting with Saddam are not known, they said.

Shiite Iran protested the alleged arrest of Khoei, who is 91. Iraq has accused Tehran of fueling the revolt against Saddam that began after the allied rout in the gulf war.

- Iraq's foreign minister, Tariq Aziz, complained to the United Nations in a message released Friday that "armed gangs" had infiltrated into Iraq from a neighboring state and "committed acts of murder, destruction, arson and looting." The official Iraqi News Agency said the message was sent to U.N. Secretary General Javier Perez de Cuellar on Wednesday.

Reporters who were taken to Karbala on Thursday said hundreds of bodies were still lying in the streets of the city, which was seriously damaged in the fighting.

- At the United Nations, the Security Council's sanctions committee met Friday to consider lifting restrictions on food imports for Iraq.