BAGHDAD - The US military on Wednesday charged publicly for the first time that Shiite Iranian intelligence agents were supporting Sunni extremists who fight against American-led forces in Iraq.
Over the past two years, Washington and top US commanders have repeatedly accused Iranian elements of aiding Shiite militias in their sectarian fight against Sunni Arabs and in waging attacks on US troops in Iraq.
But displaying what he said were newly manufactured Iranian weapons found in Baghdad, Major General William Caldwell said US authorities were now aware of Iranian help to the Sunni extremists who lead the anti-American insurgency.
"We do have now some information that Iranian intelligence agencies have supported some Sunni extremist groups," the military spokesman said.
He did not name those groups but said the latest indication of Iranian influence on insurgents came after debriefing some security detainees.
Caldwell charged that Iranian intelligence agencies were continuing to train armed Iraqi groups.
"This training is provided by surrogates of (Iranian) intelligence services," he said. "There are groups receiving training in Iran and modern weapons are smuggled in Iraq to be used against Iraqi and coalition forces."
"We know that training has been going on as recently as this month."
The US commander said Iranians were also training Iraqi groups on how to assemble explosively-formed projectiles -- a type of armour-piercing roadside bomb that has caused many coalition casualties.
"We know that training goes down there in Iran," Caldwell stressed.
Such devices have been blamed for the deaths of at least 170 US service personnel since May 2004. The white-hot slug of molten copper they emit when they explode can cut through the armoured skins of troop carriers.
These bombs have been employed to devastating effect, largely in Baghdad and the southern Shiite regions of Iraq.
It is still unclear whether Sunni insurgent groups in regions such as Anbar province -- a hotbed of anti-American forces -- have procured such explosives.
Caldwell displayed a cache of recently made explosives, bearing dates of 2005 and 2006, which he said were made in Iran and were found on Monday in a black Mercedes car in Baghdad`s Sunni district of Jihad outside a house.
On Wednesday, the United States also ruled out releasing five Iranians held in Iraq since January, despite warnings from Tehran it was unlikely to attend a May conference on Iraq`s security unless they were freed.
White House national security spokesman Gordon Johndroe said they were not expected to be freed in the near future. The US military believes the five are intelligence officers and accuses them of aiding the insurgency.
Caldwell also revealed that four US Apache helicopters were hit during a raging battle with militants in the capital`s Al-Fadhel district on Tuesday in a fight that left four Iraqi soldiers killed and 16 US soldiers wounded.
Earlier Wednesday, US military spokesman Lieutenant Colonel Scott Bleichwehl said 20 militants had been "killed in action" during the fight, which erupted in the heart of the Iraqi capital.
An Iraqi statement issued on behalf of Operation Fardh al-Qanoon (Imposing Law) -- the security plan in Baghdad -- said "19 terrorists" were killed over the past 24 hours in the central Rusafa district where Al-Fadhel is.
Iraqi and US troops have waged a massive military clampdown in Baghdad for two months that has seen American officials upbeat about signs of progress.
But the International Committee of the Red Cross said in a new report that the operation had not yet stabilised Baghdad.
"It`s clear for us that the humanitarian situation is steadily worsening and affecting in one way or another, directly or indirectly, all Iraqis today," ICRC`s director Pierre Kraehenbuehl told journalists in Geneva.
Iraq`s key Shiite political bloc also issued another threat to withdraw support for Baghdad`s embattled Shiite-led government.
The group of radical cleric Moqtada al-Sadr said it would withdraw support after Prime Minister Nuri al-Maliki rejected demands to set a time-table for the withdrawal of US troops from Iraq.
The group has 30 MPs in the 275-member parliament and six ministers in Maliki`s cabinet. Any walkout by the faction would be the second in less than five months and underscore the premier`s vulnerability.

04/11/2007 15:30 GMT