Just when the Mahdi Army seemed set to consolidate its dominant position over large areas of Iraq, Moqtadr al-Sadr, the group's fiery leader has ordered his foot-soldiers to stand down.

In a statement read out by Sheikh Hazim al-Araji, one of his senior aides, the young Muslim cleric said that his fighters should suspend operations until February and ordered his political offices closed for three days.

“I direct the Mahdi Army to suspend all its activities for six months until it is restructured in a way that helps honour the principles for which it is formed,” read the statement, which was issued in the Shia Muslim holy city of Najaf.

Although no reason was given for the move, it was seen as an attempt to halt the outbreak of bloody inter-Shia violence which erupted earlier this week in Kerbala.

Reports from the holy city, south of Baghdad, said that 52 were killed and 300 injured in clashes between Mahdi Army gunmen and members of the rival Supreme Islamic Iraqi Council (SIIC).

Al-Sadr may have been forced to act because of fears that the clashes threatened to spread to other Shia cities across southern Iraq, where offices belonging to the SIIC were set on fire Tuesday night.

The Mahdi Army, which was founded in 2003 as a rag-tag militia loyal to al-Sadr, has since emerged as one of the most powerful forces in Iraq. It boasts thousands of fighters. It is accused of receiving arms, training and funding from Iran. It controls large swathes of Baghdad and is the dominant force in Basra and other Shia cities, where it often controls the local security forces.

With Britain set this week to withdraw the last of its soldiers from the centre of Basra and with the likely drawdown of US forces from Iraq next year, the Mahdi Army should be in a position to become one of the most powerful groups in Iraq.

That may offer a clue into al-Sadr’s unexpected order today. The cleric, who rarely gives interviews but does deliver angry sermons against the US military occupation of Iraq, knows that his ambitions will be wrecked if his loose band of followers are dragged into an inter-Shia war.

Until now Iraq’s majority Shia community has stuck together. Rival groups agreed to stand on one electoral list in the last elections, where they emerged with a comfortable majority.

But even before this week’s fighting in Kerbala there were signs of deep cracks in the Shia ranks with rival militias and leaders vying for power.

Al-Sadr will have to use the next six months to reorganise his force, try to discipline unruly local commanders and turn this chaotic force into a capable organisation.

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