KUFA (Iraq)  - Anti-US Shia leader Moqtada Sadr on Friday called on his followers to "sign with their blood" a pledge to resist occupying forces in Iraq and other Muslim countries. Sadr urged "believers to sign with their blood an oath of allegiance to Imam Mahdi," in a statement read during Friday prayers by Sheikh Assaad al-Nasseri in the Shiite holy city of Kufa, south of Baghdad. The pact commits believers to "take part in resistance in all the Muslim countries and especially Iraq, militarily and ideologically, to the occupiers, colonisers and secular Western thought," the Imam said. The pact must include a person's name, country and details of where the signing occurred, and to pledge allegiance, a person must cut their thumb and leave a bloody fingerprint on the paper. "I think of all Muslims, especially in Iraq, as my brothers and I would never do anything to harm their blood, their goods or their dignity," the statement added. Sadr's powerful Mahdi Army militia has frequently been accused of attacking Sunni Arabs, particularly in Baghdad, in a key factor that led to the creation of single-faith religious districts. "My only enemies are the occupiers, the infidels, colonisers and invaders. I am not negotiating with them over the signing of a truce and will not sit at the same table as them as long as I live," the statement said. The Sadr movement's chief spokesman Salah al-Obeidi said the campaign had already begun. "It is about emphasising the worship of Allah rather than politics, the fact that the resistance does not have to end as long as there is an occupation, as well as all aspects of resistance to the occupier," he said. "It is equally a call for unity for all Iraqis," he added. Sadr, who US forces believe is in Iran, announced in June that he would replace the 60,000-strong Mahdi Army with a leaner and meaner fighting force to target the US-led occupation. A ceasefire between Sadr and the US-led coalition forces drawn up a year ago has been a key factor in violence levels dropping to four-year lows. Meanwhile, two American soldiers have died in Iraq during the last 24 hours, including one marine who was shot dead and another in a non-combat related incident, the US military said on Friday. An investigation was underway into the death of the soldier who was killed on Friday for non-combat reasons, the US military said. It did not provide other details. Earlier the military said that the marine was shot dead on Thursday when his patrol came under small-arms fire just east of Fallujah, west of Baghdad. Fallujah, in Al-Anbar province, was the epicentre of violent clashes between American forces and Sunni insurgents after the fall of the regime of Saddam Hussein in April 2003. The city was literally razed to the ground during a large-scale American offensive in November the following year. The violence began to decline late in 2006 when local tribes, tired of Al-Qaeda extremism, turned against them and joined American troops in fighting the jihadists. The latest deaths brings to 4,142 the number of US soldiers killed in Iraq since the 2003 invasion, according to a count by AFP based on independent website icasualties.org.