Iraqi insurgents last night threatened to send President Bush’s 22,000 new troops home in body bags as details emerged of the new Baghdad crackdown at the core of his “surge” strategy.

The Shia-led Government of Nouri al-Maliki reacted positively, but there is widespread scepticism as to whether it will confront Shia militias within its own hardline parties. On the streets there are near-universal predictions — from Sunnis and Shias alike — that the plan will join previous failed initiatives.

The most strident reaction came from hostile insurgents in Salahaddin and other Sunni Triangle towns north of Baghdad. The Bush-Maliki plan to deploy tens of thousands of troops in the satellite towns is widely regarded by Sunni residents as evidence of US complicity with their Shia enemies.

“Twenty thousand soldiers will never be able to achieve what 140,000 have failed to achieve so far, and the fate of the new soldiers will not be any better than for those who were here before them,” said Abu Moath, an insurgent with the Islamic and Nationalist Front for the Liberation of Iraq. “They came here to kill innocent Iraqis so they should be all killed the same way.”

Ahmed al-Hassani, of the hardline Ansar al-Sunna, said: “We will keep going in our war that does not accept any midway solutions. Either they pull out of our country or the war will continue until we achieve victory.”

Officials insist that the joint US-Iraqi Baghdad crackdown will aim at both sides. But although some raids have been launched against Hojatoleslam al-Sadr’s al-Mahdi militia, the Government appears to have little appetite for a full-on confrontation.

One al-Maliki aide told The Times that the Baghdad offensive would first concentrate on outlying Sunni insurgent strongholds that “choke” the capital — such as Abu Ghraib, Latifiya and Salman Pak — rather than taking on al-Mahdi Army.

“The Prime Minister has said that if the surge is used to tackle the areas sending car bombs into Baghdad he will approve it, but if it is used to do the same as before, he would not be very enthusiastic,” he told The Times.

“He argues that the way to deal with the Mahdi Army is to bring down the level of terrorist attacks so ordinary Shia don’t feel the need for the Mahdi. Right now they think the Mahdi is bad, but without them they would be killed by al-Qaeda and the others.”

After four to eight weeks — once ordinary Shias see a reduction in insurgent killings — the Government would be in a stronger position to persuade the militia to disband. While the plan’s exact timing and focus are being kept secret, Lieutenant-General Nasir Abadi, the Iraqi Army’s Deputy Chief of Staff, confirmed to The Times that it would “definitely” hit Bagh dad’s outer ring, where insurgents operate safely within Sunni neighbourhoods. “That is why we need the extra troops, to have operations inside and outside simultaneously,” he said at the Defence Ministry in Baghdad. “Some we will be bringing from our own forces in the north and south, and some may be from the coalition.

“When we clear an area, we have to hold it and then bring in economic benefits, which will get the politicians together. I think it is a good strategy.”

Baghdad’s streets were much quieter than usual yesterday, many shopkeepers slamming down their metal shutters, nervous of impending battles against Sunni and Shia gunmen.

In the giant Shia slum of Sadr City, the Baghdad stronghold of the radical cleric Moqtada al-Sadr, his al-Mahdi Army is ordering every man aged 15-45 to register for combat. One al-Mahdi fighter told The Times’s Iraqi staff that they had been put under orders not to seek confrontation. “We expect this new American plan to try to take on our leadership, not to go after every fighter, weapon and vehicle. We will keep our leadership in safe areas.”

• US troops arrested six Iranians at an Iranian government office in the Kurdish city of Irbil in northern Iraq yesterday, prompting an angry reaction from Tehran, which accused Washington of trying to “create tension” with Iraq’s neighbours. The raid — during which witnesses said troops used stun grenades and hauled down an Iranian flag — came as President Bush accused Iran and Syria of helping insurgents and promised to “interrupt” the flow of money and weapons.

  US officials denied that the building was a consulate, as claimed by Iran. Muhammad Ali Hosseini, the Iranian Foreign Ministry spokesman, initially said it was a “diplomatic mission” but later downgraded it to an “office of relations”.

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