(Updates with quotes, more detail)

BAGHDAD, June 13 (Reuters) - Iraqi Prime Minister Nuri al-Maliki on Wednesday blamed Sunni Islamist al Qaeda and supporters of Saddam Hussein for an attack on a revered Shi'ite shrine in the city of Samarra.

Speaking on state television, Maliki said he believed other mosques could be targeted and that he had asked Iraq's security forces to step up security around them.

He said he had ordered the arrest of all the security forces responsible for protecting the shrine.

"I call on everyone to stand together against those who want to stir strife," he said.

(Baghdad newsroom, editing by Dean Yates)

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