Moqtada Sadr, the radical Iraqi Shia cleric whose militia led uprisings against US troops in Najaf has told the BBC armed "resistance is legitimate".
The radical young cleric has a band of loyal followers
Speaking to Newsnight, Mr Sadr said that even US President George W Bush would agree that fighting an occupation force was a correct course of action.
However, he did call upon Iraqis to exercise restraint with US troops.
And he said he would not interfere with the democratic process, saying "Whoever wants to take part, let him do so".
"Resistance is legitimate at all levels be it religious, intellectual and so on," Mr Sadr said, in his first interview with Western media.
"The first person who would acknowledge this is the so-called American President Bush who said 'if my country is occupied, I will fight'."
In the past Mr Sadr has called for a national rebellion against foreign troops and sent out his militiamen, the Mehdi Army, to confront the "invaders" and Iraqi police.
Weeks of clashes ended with an agreement under which Mehdi Army fighters agreed to hand over their weapons. US plans to arrest Mr Sadr were quietly dropped.
Speaking in the interview, broadcast on Monday night, Mr Sadr said he believed "America does not want confrontation".
"So I call upon other parties like the Iraqi army and the Iraqi police to exercise self-restraint with Iraqi people and not be provoked into them or the occupying forces as this isn't in the interest of Iraq," he said.
"I also call on the Iraqi people to exercise restraint and not get enmeshed in the plans of the West or plans of the occupation that wants to provoke them."
Mr Sadr argued that it is the presence of foreign troops which is the cause of Iraq's current problems.
"The occupation in itself is a problem. Iraq not being independent is the problem. And the other problems stem from that - from sectarianism to civil war," he said. "The entire American presence causes this."
Refusal to engage
Iraq is expected to unveil a new constitution on 15 August, but Mr Sadr, who is a figurehead for many of Iraq's poor Shia Muslims, said he would not play any part in drafting that constitution or take on an official political role as long as the US troops remain.
"I personally shall not interfere. I say that our constitution is the Koran and the Sunnah and I refuse any political role while the occupation is present," he said, although adding that he would not stop any others participating.
The interview was conducted over the last two weeks.
Newsnight's interview with Moqtada Sadr was broadcast on Monday 18 July.