BAGHDAD — Iran called off further Iraq security talks with Washington until American forces stop their crackdown on Shiite militias, but the military brought more air power into the fight yesterday and escalated its accusations of Iranian backing for extremists.

The latest flare-up has put Iraq’s government in a bind as it seeks to stamp out armed Shiite gangs but worries about angering Shiite heavyweight Iran, which has close ties to the core of Iraq’s political leadership.

Washington has long accused Iran of arming and training some Shiite militia factions. The accusations were sharpened yesterday as the military said detainees described being trained at bases outside Tehran by militants from Hezbollah, an Iranian-aided faction based in Lebanon.

Iraq’s Shiite-led government said that the battles against militias would continue even if Iran pulled out of the security talks. Three rounds have been held at the ambassador level since May and marked rare direct diplomatic contact between the two nations, which have had no formal relations since shortly after Iran’s 1979 Islamic Revolution.

There are also worries that Sunni extremists are regrouping. Attacks blamed on Al Qaeda in Iraq have claimed dozens of lives in recent days, including an attack yesterday that killed at least 10 Iraqi soldiers and wounded 13 at a checkpoint in Diyala province northeast of Baghdad, the U.S. military said.

In Tehran, Iran’s Foreign Ministry spokesman, Mohammad Ali Hosseini, said talks could not be held under current conditions.

“What we are witnessing is open and extensive bombing of the Iraqi nation, while the main goal of talks with the American side would have been security and peace in Iraq,” Mr. Hosseini said. “It is a matter of doubt that the U.S. is pursuing a solution for the crisis, which was caused by them.”

In Baghdad’s Sadr City, a Shiite slum where 2.5 million people live, American and Iraqi forces have been under sustained attacks by militias including members of the powerful Mahdi Army led by the anti-American cleric Moqtada al-Sadr.

Hundreds of people have been killed in Baghdad and the southern city of Basra since late March when Iraq’s prime minister, Nouri al-Maliki, launched an offensive against Shiite militias and so-called “special groups” with suspected ties to Iran.

Yesterday, the U.S. Air Force unleashed one of its most potent weapons, the AC-130 gunship, against Shiite extremists in Baghdad. The U.S. military said it killed at least nine militants in clashes since Sunday.

[Also yesterday, a leading Arab newspaper published excerpts of Saddam Hussein’s prison writings, in which he wrote he feared catching AIDS or other diseases during his U.S.-supervised captivity, the AP reported.

The London-based Al-Hayat said the comments came in portions of Saddam’s prison diaries that it obtained from American authorities. The U.S. military confirmed some of the late Iraqi leader’s writings had been released.]