At least two followers of Shi'ite leader Moqtada Sadr were killed yesterday after throwing themselves in front of US tanks during a demonstration in central Baghdad, a police officer said. "There were two or three dead among the protesters who threw themselves under American tanks which could not avoid them on Tahrir Square," said Sergeant Abbas Mohamad. The protest turned violent as some supporters of Sadr threw themselves at the US tanks. Huge protests were also held in Najaf and as far south as Amara, while unarmed militiamen from Sadr's Mehdi Army paraded in Sadr City, a sprawling Shi'ite neighbourhood of the capital. Early yesterday, Sadr supporters took to the streets of Najaf, reacting to rumours that Spanish coalition soldiers had detained Mustafa Yaacubi, the head of his office in the city. Spanish commanders "categorically" denied the charge in a statement that was distributed to the crowd outside the headquarters of the Spanish-led Plus Ultra Brigade in Najaf until mid-evening. The protestors dismissed the denial, demanding the release of Yaacubi. Sheikh Qais al-Khazaali, the head of Sadr's office in Baghdad, warned that his movement would react if Yaacubi was not quickly released. "This is a new provocation by the coalition forces," Sheikh Khazaali told AFP. "If he is not quickly released, our movement, our leadership and our supporters will react with the means at our disposal." Meanwhile, in the latest assault on Iraq's US-trained security forces, gunmen killed four people in two separate attacks on police south of Baghdad yesterday. In the first attack, the department chief of Mahmoudiya, 30km south of Baghdad, was driving from the capital to his home when gunmen killed him and his driver, police Lieutenant Ala'a Hussein said. In another incident, six attackers shot at a four-man police patrol in Mahmoudiya, killing one and wounding three, police officer Khaldoon Al Gurairi said. Guerillas often target police because they view them as collaborators with the US-led occupation. **PHOTO CAPTION*** Iraqis burn a US flag while one of them hits it with a sandal during a demonstration held in Baghdad, in front of firebrand Shiite Cleric Moqtada al-Sadr's newspaper office, the al-Hawza al-Natiqa daily, to protest against the coalition provisional authority (CPA) order to close the newspaper. (AFP/File/Ahmad Al-Rubaye)