Iraqi security forces backed by U. S. helicopters battled hundreds of militants linked to al-Qaida near the holy Shiite city of Najaf, some 160 km south of Baghdad, killing up to 300 of them, Iraqi official and army sources said on Monday.

"The situation is under control now and by Monday morning our forces started to search the area after the battles that resulted in the killing of some 300 terrorists and the detention of 13 others," Colonel Ali Jreio, the commander of the Iraqi army in Najaf told the Iraqi state-run television.

However, Jreio's figures could not be independently confirmed as the Iraqi Defense Ministry said it could not yet give the exact toll because sporadic fighting still went on.

On Sunday, police source told Xinhua that about 250 militants were killed during a day-long battle outside Najaf when Iraqi security forces fought fiercely against a group of radical militants who planned to attack Shiite clerics during Shiite's Ashura commemorations.

Abdul Husein Attan, deputy governor of Najaf province told reporters that an extremist Sunni group called al-Qaida in Iraq Organization was behind the group of radical militants.

"I can confirm that the al-Qaida in Iraq is behind this group," Attan said in a news conference in the city of Najaf.

"Based on the confessions of interrogated militants and other information, this group intended to attack Shiite clerics and take control of Najaf and its holy sites," he added.

On Sunday, explosions and heavy machine-gun fire were heard since early morning while U.S. helicopters were circling above the battle area, witnesses said.

During the battle, the U.S. army suffered the loss of two soldiers and one Apache helicopter, according to the U.S. military statement.

Tens of thousands of Iraqis marched on Monday in the Shiite cities amid a tight security measures to commemorate the slaying of the Prophet Mohammed's grandson Imam Hussein in the Shiite holy city of Karbala in the seventh century.

Thousands of men wearing black clothes, thumbing their chests marched in the streets of Karbala, some 110 km south of Baghdad.

Groups of Shiites celebrated Ashura with traditional flagellation ritual which involves the use of a chain with a set of curved knives at the end as a part of mourning ceremonies commemorating Hussein's martyrdom.

Ashura has been marred in the past by attacks by Sunni extremists which left scores dead.

Source: Xinhua