MOSUL, Iraq (IslamOnline.net & News Agencies) - The messy situation in occupied Iraq continued Friday, May 7, to claim more lives in all directions as a tense standoff, threatening a bloody confrontation, remained in the cities of Najaf and Karbala between the U.S.-led occupation forces and followers of an Iraqi defiant Shiite scholar.

Four Iraqi policemen were killed in a roadside bomb explosion in northern Iraq Friday as two Polish and Algerian reporters were shot dead in the south of the country.

The bomb detonated as a patrol was passing through the al-Jadida district in the southern part of Mosul, police and hospital officials told Reuters.

Police said there was a gun battle with the attackers immediately after the attack, but no one was arrested.

Mosul, about 400 km (240 miles) north of Baghdad, has seen regular drive-by shootings and occasional bomb attacks, aimed mostly at Iraqi police, the civil defense force and others seen by local inhabitants as collaborating with the foreign forces occupying the oil-rich country.

In the meantime, a Polish and an Algerian journalist, both working for Poland's TVP television, were shot dead by gunmen in Latifiya, their Iraqi companion Assir Kamel al-Kazzaz told Agence France-Presse (AFP).

A Polish cameraman was also wounded in the attack, he said, as a Polish Embassy official confirmed the deaths.

Latifiya is about 20 miles south of Baghdad on the road to Babylon, where the headquarters of the Polish military force in Iraq is based.

Poland is a staunch supporter of the U.S.-British invasion-turned-occupation of Iraq and has about 2,400 troops in the country and leads a multinational stabilization force in south-central Iraq.

A reporter for the American news network CNN was killed in a similar ambush in January on the same deadly stretch of road.

Sadr appeared in a mosque of the city to lead the prayers, as his followers and U.S. troops traded heavy fire outside a mosque in Karbala Friday afternoon, turning the city into a ghost town at an hour when people normally gather for weekly prayers.

The shooting lasted a few minutes as the soldiers tested defenses outside Sadr's office next to the Mohkayem Mosque, which is not far from the heart of the city, home to two of the most sacred shrines for Muslims in general, and Shiites in particular, an AFP correspondent said

Sadr's Mehdi Army militia had gone on the counter-attack Thursday night in Karbala and the southern cities of Amara and Nassiriyah, various sources said earlier Friday.

The violence erupted after the U.S. army seized the governor's building in the shrine city of Najaf where Sadr, who has led a month-long fighting against the American forces, has barricaded himself with supporters.

On the other hand, a senior Shiite scholar Sheikh Sadreddin Kubanji called in Friday prayers for the Mehdi Army militia to leave An-Najaf.

"Listen to the advice of the learned ones. You are our beloved youth and we care about you, but go back to your home where you came from and fight the occupation and the Baathists there," Kubanji told thousands of worshippers at the Imam Ali Mausoleum, one of the most revered shrines in Islam.

But "the Najafis will be responsible for protecting Najaf," said Kubanji, close to Shiite leader Ayatollah Ali al-Sistani.

Kubanji's sermon came after Shiite religious and tribal leaders met Tuesday, May 6, in Najaf and called on Sadr to end the clashes.

U.S. soldiers on a military vehicles were seen moving through Iraqi Shiite Muslims loyal to Sadr, as they prepared to perform the Friday midday prayers at Baghdad's Sunni neighborhood of Adhamiya.

Any such move would cause widespread fury among Iraq's Shiites, already infuriated by the more than one-year occupation of the oil-rich country.