WASHINGTON, April 1, 2008 (AFP) - The Iraqi government's failure to wipe out Moqtada al-Sadr's Mahdi Army during a crackdown in Basra last week may leave the group stronger in the long run, a senior US senator said Tuesday.

Joseph Biden, chairman of the powerful Senate Foreign Affairs Committee, told reporters on a conference call that despite Prime Minister Nuri al-Maliki's crackdown, Shiite cleric Sadr 'lives to fight another day.'

'One of the things that concerns me is that this is a little bit like what happened to Hezbollah in Lebanon (in 2006)... the Israelis used full force that they had in Lebanon and Hezbollah survived and they grew in strength as a consequence,' he said.

'Here, Maliki says he's going down and he's going to take out all these malcontents, as well as take out Sadr and his Mahdi Army. And it looks to me like, at least on the surface, Sadr may have come out a winner here.

'You know, he lives to fight another day.'

A week ago, Maliki ordered a military crackdown on militants in the southern oil city of Basra, mostly from Sadr's Mahdi Army militia.

The offensive quickly set off a wave of clashes between the militiamen and security forces in Basra and other Shiite areas of Iraq in which at least 461 people were killed and more than 1,100 wounded.

Sadr reined in his fighters and ordered them off the streets Sunday, while Maliki ordered his security forces Tuesday to stop random raids and arrests.

Biden said 'there's a lot more to learn' about the ceasefire and whether there was 'any serious damage done' to the central government or to Sadr.

He said he had not been officially briefed on the situation but believed the US did not play a large part in negotiating the ceasefire.

'There's some reason to believe that that may very well have occurred in Iran through the Iranians,' he said.

Biden was speaking a week before he presides over a hearing in which US ambassador to Baghdad Ryan Crocker and General David Petraeus, the commander of US forces in Iraq, will brief Congress on the situation in the country.

He expressed skepticism about President George W. Bush's assertion Friday that the upsurge in violence was a 'defining moment' for Iraq's progress and particularly for Maliki's government.

'Using the phrase 'defining moment' makes it sound like this democratic leader in Baghdad decided to put a stop to the thuggery of the extreme elements of the Shia movement and move with his forces of democracy against them,' Biden said.

'Well, that ain't the way that place plays out.'

Biden said 'everybody knows Sadr's not a good guy' but noted: 'There's a lot of other bad guys in this Shia (governing) coalition. And so, which bad guys are we working with?'

The question was not whether there should have been a ceasefire with Sadr's forces but what the Iraqi government hoped would come of it, and 'who did they have to be in league with who aren't good guys?' he said.

'I don't know this administration has a policy,' he concluded.

He added that he would be pressing Crocker and Petraeus on the effect of last year's 'surge' of troops into Iraq and plans for the future, 'both in terms of US force levels and US policy for succeeding in Iraq.'