About 50 suspected insurgents attacked a US base in the center of a city north of Baghdad on Friday, sparking a battle with US soldiers and helicopters that left at least six militants dead, the Iraqi army said.

The fighting took place in Baqouba, a Sunni insurgent stronghold that has seen a recent spike in violence largely blamed on militants who fled a three-month-old security crackdown in Baghdad.

In Iraq's capital, two Iraqi journalists working for ABC News were slain as they drove home from work, the American television network announced on Friday.

Unidentified assailants waylaid the car carrying cameraman Alaa Uldeen Aziz, 33, and soundman Saif Laith Yousuf, 26, and shot them dead, the network said.

Journalists have been frequently targeted by extremists in Iraq, with more than 100 reported killed since the war began.

Meanwhile, the massive search for three missing US soldiers believed to have been kidnapped by Al-Qaida-linked insurgents entered its seventh day.

Colonel Michael Kershaw, the commander of the 2nd Brigade Combat Team, 10th Mountain Division, who was overseeing the mission, said the teams were talking to local Iraqis, hoping to find information that would lead them to the soldiers.

"Everyone is motivated and knows the importance of finding the soldiers," he said in a statement from Quarghuli, a village 20 kilometers south of Baghdad where a May 12 ambush killed four US soldiers and an Iraqi, and left three American troops missing.

The fighting in Baqouba began about 7 am on Friday, the day of rest in Muslim Iraq, when insurgents opened fire on a US-Iraqi base in the center of the city, about 60 kilometers northeast of Baghdad.

About a half hour later, US reinforcements arrived, killing at least six insurgents, the Iraqi army officer said. He spoke on condition of anonymity because he is not authorized to speak to the media.

Residents said the fighting sent smoke billowing up from neighborhoods in the area.

Source; China Daily/Agencies