Iraqi airmen who fled to neutral Iran are being held in prisoner of war camps, and their top-of-the-line warplanes will not be used against the allies in the Persian Gulf war, an Iranian source in the United Arab Emirates said Thursday.

The source, an Iranian government official with close links to President Ali Akbar Hashemi Rafsanjani, said the Iraqis are being treated humanely but are not allowed to leave their camps.Iraqi warplanes, including French-built Mirage F-1EQ-5 fighter bombers, Soviet-built MiGs and Chinese-built Badgers carrying Exocet missiles, have been transferred to heavily guarded inland Iranian air bases, the source said.

Although the Bush administration has publicly accepted Iranian assurances that the Iraqi planes will not be used to strike allied warships in the gulf in a last-ditch Iraqi attempt for victory, allied commanders in the field have been quoted as expressing caution about Iranian intentions.

"Neither the planes nor their pilots will use Iran to strike another country," the Iranian said. "Such a move is impossible."

"The Iraqi airmen are being well-treated in prisoner of war camps in Iran," the source told United Press International in a telephone interview.

The Iranian source declined to say how many Iraqis were involved or how many Iraqi planes were in Iranian custody.

- BLACK RAIN IN IRAN - The environmental fallout from the gulf war is causing deep concern in Iran, where black rain fell this week in the Iranian port cities of Gonaveh and Bushehr, 175 miles from the war zone, the Islamic Republic News Agency said.

In a dispatch monitored in Athens, IRNA said Iran faced major pollution problems with sulphur, nitrogen oxide and soot at an unprecedented high level over several cities. The black rain is believed coming from fires set off by the fighting in Kuwait.