An Iranian dissident group based in Iraq said Monday Iranian troops launched a major offensive across the border against their positions inside Iraqi territory.

A spokesman for the Baghdad-based Mojahedin Khalq Organization said Iranian troops began an offensive against positions of the rebel National Liberation Army of Iran near Qasr Shirin hours before dawn, and heavy fighting was still raging more than nine hours later.The purpose of the offensive was to dislodge units of the NLAI, the military wing of the Mojahedin Khalq, from high ground they recently captured from the paramilitary Iranian Revolutionary Guards north of the Iraqi border city of Haneqin, the spokesman said.

He said the Iranian rebels "countered the attack and blocked the guards' advance," killing some 300 Iranian government troops at Aqdagh Saghir.

There was no word from Iran or independent sources on the reported Iranian offensive inside Iraqi territory, but Tehran radio said Revolutionary Guards clashed with forces of the Mojahedin Khalq inside Iran in the Qasr Shirin area.

Tehran radio's version said the Mojahedin forces suffered heavy casualties in the fighting.

The NLAI rebels captured the high ground at Aqdagh Saghir and Movarid in their own offensive against Iranian guards about a week ago, the Mojahedin spokesman said.

Thousands of Iranian Revolutionary Guards took part in the latest offensive, using tanks and armored vehicles, the Mojahedin spokesman said. The Mojahedin have reported clashes between Iranian troops and dissident forces inside Iraqi territory since March 11.