Iraq's foreign minister on Wednesday said security talks between Iran and the United states have been indefinitely postponed due to "exchange of accusations" between the sides.

Tehran on Monday called off further Iraq security talks with Washington until U.S. forces stop their crackdown on Shiite militias as Washington escalated its accusation of Iranian backing for extremists. U.S.-led forces are locked in fierce street battles in Sadr City, a Shiite militia stronghold in Baghdad.

"It is impossible to hold a new round (of talks) because of exchange of accusations between the two sides," Hoshyar Zebari told a news conference in Baghdad. "The negotiations are postponed indefinitely because of tense atmosphere."

Zebari said "resuming dialogue" between Iraq, Iran and the United States was crucial.

"We had three important rounds but they yielded no fast results," said Zebari, adding that Iraq's efforts to hold the next round of talks have failed.

U.S.-led forces are fighting Shiite extremists as well as Sunni insurgents from Al Qaeda in Iraq.

The Dubai-based al-Arabiya television on Wednesday identified the leader of Al Qaeda in Iraq, citing an Iraqi police official, and said the real name of Abu Omar al-Baghdadi, who allegedly heads the Islamic State of Iraq, is Hamid Dawoud al-Zawi.

The U.S. military in Iraq on Wednesday did not confirm the report, citing security reasons.

"Regardless of his 'real' identity, however, al-Baghdadi is a 'figurehead' to give the public appearance of Iraqi leadership of Al Qaeda in Iraq," the military said in response to an e-mailed query. "The real leader of Al Qaeda in Iraq is the Egyptian Abu Ayyub al-Masri."

Originally from Haditha, al-Baghdadi served in the Iraqi army under Saddam Hussein, then joined al-Qaida in 2003, the police official told Al-Arabiya.

The clashes in the Sadr City district erupted after an Iraqi government crackdown on armed Shiite groups began in late March. The U.S. military is now trying to weaken the militia grip in the teeming slum neighborhood and disrupt rocket and mortar strikes on the U.S.-protected Green Zone.

But fresh salvos of rockets from militants arced over the city, wounding at least 23 people on Tuesday and drawing U.S. retaliation that escalated civilian panic and flight to safer areas.

The military on Wednesday said four rockets fired by Shiite extremists from Sadr City landed in residential areas in downtown Baghdad and wounded seven Iraqis Tuesday evening. An attack aircraft responded on Tuesday evening, killing one militant, the military said.

Earlier Tuesday, 16 Iraqis were injured in similar attacks.

The U.S. military on Wednesday said four militants and two U.S.-allied Sunni fighters were killed in northwest Baghdad when the Sunni guards responded to an attack Tuesday evening on a checkpoint northwest of Baghdad, killing three attackers. Two Sunni guards later died in a hospital, it added.

Clashes between U.S.-led forces and Shiite extremists left at least 28 people wounded in Sadr City, Iraqi health officials said Wednesday.

In southern Iraq, gunmen killed an Iraqi army officer in a drive-by-shooting in the Shiite city of Kut, police said.