The "Battalions of the '20 revolution, the military wing of the Islamic Resistance in Iraq" announced "it would consider any foreign forces, be they Arab or Islamic, occupation forces," Al-Jazeera said.
It gave no further details, but a spokesman at the Al-Jazeera said the warning had come in a statement received by the Doha-based satellite news channel.
The Saudi proposal to send Arab or Muslim forces to Iraq was discussed by US Secretary of State Colin Powell with both Saudi leaders and Iraqi Prime Minister Allawi during a visit to the Gulf kingdom earlier this week.