A militant Somali Muslim cleric has warned of a Holy War or "Jihad" if foreign peacekeepers are deployed.
Sheikh Aweys denies terror groups operate in Somalia
Sheikh Hassan Dahir Aweys is a senior member of the Islamic courts, which has a militia, and is accused by the United States of having links to al-Qaeda.
President Abdullahi Yusuf wants peacekeepers to protect his government when it relocates from Kenya.
Somalia has not had a functioning government for 14 years and has been divided by rival warlords.
'To the death'
Mr Aweys, who denies that any terror groups operate in Somalia, said it would be the religious duty of all Somalis to fight any peacekeeping force.
"We will fight fiercely to the death any intervention force that arrives in Somalia," he said.
He also urged foreign countries not to fund the proposed peace force.
East African countries have agreed to send some 6,800 Sudanese and Ugandan troops to Somalia.
Several Mogadishu-based warlords, named in Mr Yusuf's exiled government, have also opposed the use of foreign troops.
MPs were involved in a brawl during a debate on the issue last week.
Mr Yusuf does not have a strong support base in Mogadishu, where gunmen can be seen running roadblocks on behalf of the rival warlords.