US forces and Iraqi soldiers launched a major offensive against a Shi'ite militia yesterday, killing 20 people in a raid on a mosque and pounding other positions around Najaf. The fiercest fighting in the area for weeks killed at least 34 people and wounded dozens, including civilians, overnight and seemed a definitive response to a tentative truce offer made by an aide to the cleric leading the Mehdi Army, Moqtada Al Sadr. Pools of blood lay inside the green-domed Sahla mosque, one of three main shrines in Kufa near Najaf, and spent cartridges littered the courtyard. A tank had smashed down the door of the building, and the US army said weapons were found inside. It said American soldiers had not entered the mosque, instead an Iraqi "counter-terrorism force" had been sent in. **PHOTO CAPTION*** Iraqi men bury the body of a Shi'ite motorist killed by U.S. troops in Najaf, May 22, 2004. (REUTERS)