* Maliki says crackdown shows he is not sectarian

* Sadrists deny truce means they have to hand in guns

* Iran played a role in truce accord, Iraqi MP says

(Adds Sadr spokesman comment on weapons)

By Waleed Ibrahim and Aseel Kami

BAGHDAD, May 12 (Reuters) - Iraq's prime minister said on Monday a crackdown on Shi'ite militias proved his government was not sectarian, in the face of persistent accusations by Sunni Arabs that he has favoured Shi'ites since taking office.

Nuri al-Maliki, a Shi'ite Islamist, ordered an operation against Shi'ite militias in the southern city of Basra in late March to break their grip on Iraq's hub for oil exports.

The offensive sparked fierce resistance from the Mehdi Army militia of Shi'ite cleric Moqtada al-Sadr. While fighting with security forces eased in Basra within a week, clashes with Shi'ite gunmen raged in the cleric's Baghdad stronghold of Sadr City until an agreement last weekend to halt fighting.

"The events of the past weeks have proven that we are neutral, not biased, that we did not take the side of this party or this sect against another," Maliki said of his Shi'ite-led government in a speech to parliament.

"We have also proven there is no security for any sect unless other sects can be guaranteed their security."

Since becoming prime minister in May 2006, Maliki has faced constant criticism from minority Sunni Arabs that he has promoted the interests of majority Shi'ites ahead of the country's other sectarian and ethnic groups.

Sadr's movement in parliament and the ruling Shi'ite alliance reached an agreement on Saturday to end fighting in Sadr City and allow aid to reach the slum's 2 million residents.

However, sporadic clashes continued, indicating some gunmen claiming loyalty to Sadr ignored the deal. It has long been unclear how much control the anti-American Sadr has over some of the tens of thousands of gunmen who profess allegiance to him.

U.S. forces killed three gunmen who attacked their patrols on Sunday and overnight in Sadr City, the U.S. military said.

And in a sign of early disputes between the factions that signed the agreement, the Sadr movement denied it meant militiamen had to hand in any weapons.

Members of the ruling alliance said heavy arms should be given up. This would include rocket and mortar launchers.

"The talks ... concentrated on two points only: a ceasefire and an end to displaying arms in public," said Salah al-Ubaidi, Sadr's spokesman.

SHI'ITE RIVALRY

The main Sunni Arab bloc withdrew from Maliki's government last August, complaining that Sunni Arabs were being marginalised and did not have enough say in security affairs.

But politicians from across Iraq's ethnic and sectarian divide -- apart from Sadr's political movement -- have rallied behind the prime minister's crackdown on militias.

Maliki says the operations have been intended to impose law and order. Sadrist officials have accused him of targeting the Mehdi Army and of trying to sideline the cleric's popular mass movement before provincial elections in October.

The movement, which boycotted the last local elections in 2005, is expected to do well at the expense of other Shi'ite parties supporting Maliki, especially in the Shi'ite south.

Politicians said they hoped the Sadr City truce would last.

"I hope this is the foundation for a wider deal that will stop us going back to the security tensions that once existed with various parties," Ali al-Adeeb, a legislator in the ruling Shi'ite alliance, told a news conference with the Sadrist bloc.

Adeeb earlier told Reuters Iran had played a prominent role in striking the agreement.

He said an Iraqi parliamentary delegation that went to Tehran almost two weeks ago asked for Iranian help because of Tehran's influence over Sadr's movement.

Adeeb's comments illustrated the growing sway Shi'ite Iran has in Iraq and could unsettle Washington.

U.S. military officials say Sadr himself is living in Iran, where he is believed to be taking advanced Islamic studies. (Writing by Tim Cocks, editing by Dean Yates and Ralph Boulton)

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