KUFA, Iraq - U.S. troops and militiamen loyal to radical Shiite cleric Muqtada al-Sadr clashed near holy shrines in Karbala today, while al-Sadr delivered a defiant sermon at a Kufa mosque. Gunmen killed two journalists from Polish television on the road to the troubled cities.

Despite the presence of hundreds of U.S. troops nearby on a mission to capture him, al-Sadr arrived from Najaf at the main mosque in Kufa surrounded by a large number of his heavily armed black-garbed gunmen, including at least one carrying an anti-aircraft gun.

"Yes, yes, to freedom! Yes, yes, to independence," several thousand worshippers chanted as the young renegade cleric delivered a sermon condemning the United States over the abuse of Iraqi detainees at Baghdad's Abu Ghraib prison.

"What sort of freedom and democracy can we expect from you when you take such joy in torturing Iraqi prisoners?" said al-Sadr, his shoulders draped with a white coffin shroud symbolizing his readiness for martyrdom.

U.S. troops have not moved to capture al-Sadr for the past four weeks as he has attended the Kufa prayers. The military has been treading carefully in its confrontation with al-Sadr and his al-Mahdi Army militia, fearing that if it is too aggressive near some of Shiism's holiest shrines it will inflame Iraq's Shiite majority.

Still, U.S. forces have intensified the crackdown over the past week, with increasingly bloody clashes in several southern cities. Large explosions and gunfire were heard today near the mosque that serves as al-Sadr's headquarters in central Karbala - about 500 yards from two major shrines. The shooting was heard soon before noon prayers.

The exchange of fire followed hours of clashes in at least three other parts of the city that lasted from before dawn until midmorning. There was no immediate word on casualties from the day's skirmishes.

Two journalists from state-run Polish television - a Pole and an Algerian - were killed as they drove from Baghdad to Najaf when gunmen in another vehicle sprayed their car with gunfire.

A Polish cameraman was wounded in the arm in the shooting, said Adam Wielgosz, an official at the Polish Embassy in Baghdad.