Tens of thousands of people have staged protests across Iraq after a bomb attack heavily damaged one of the holiest Shia’s sites.

Dozens of Sunni mosques are reported to have been targeted and six Sunnis killed after a gang blew up the dome of the al-Askari shrine in Samarra.

Iraqi President Jalal Talabani said the country must work to avoid a civil war.

In a television broadcast, Talabani, a Sunni Kurd, accused the attackers of trying to sabotage attempts to form a coalition government.

"We must... work together against... the danger of civil war," he said.

No-one has claimed responsibility for the attack on the shrine, although Iraqi television said several people had been arrested in connection with the bombing.

The BBC's Jon Brain in Baghdad says the attack was almost certainly designed to raise the existing tensions between Shia and Sunni populations.

Protests and violence broke out across Iraq:

• In Baghdad, a Sunni mosque in Baladiya district is raked with gunfire, while black-clad militiamen of the Shia Mehdi Army demonstrate in Sadr City; six Sunnis were killed in violence
• In Basra, gunmen attack Sunni mosques and exchange fire with guards at an office of the Sunni Iraqi Islamic Party
• Businesses shut down in Najaf and about 1,000 march through the streets, waving flags and shouting slogans
• Markets, shops and stalls close in Diwaniya, AP says. A Mehdi Army militiaman is killed in clashes after gunmen from the faction attack Sunni houses, Reuters news agency reports
• About 3,000 people demonstrate in the Shia city of Kut, chanting anti-American and anti-Israeli slogans and burning US and Israeli flags, AP says.

The leading Sunni religious body condemned the attack.

After assailants attacked offices of his party in Baghdad and Basra, Sunni political leader Tareq al-Hashimi of the Iraqi
Islamic Party said: "We will pursue anyone who attacks Sunnis."

The Islamic Party also demanded a curfew to protect Sunni areas; Iraqi troops patrolled Sunni districts of Baghdad and the US military said Iraqi forces had increased their presence.

As dusk fell, streets were quiet and queues formed at shops where people said they were stocking up in case of trouble.

The national security adviser accused al-Qaida followers of the bombing and said 10 people wearing the uniforms of police commandos had been arrested in Samarra.

PHOTO CAPION

An Iraqi resident stands outside a partially burnt Sunni mosque in Baghdad February 22, 2006. (REUTERS)