"It really is the systematic destruction of a country for reasons I think are more connected with oil than human rights."
The veteran campaigner's attack on the effects of Western sanctions on ordinary Iraqis came on the 10th anniversary of the start of the Gulf War and as anti-sanctions protesters prepared to converge on Westminster.
But he went on: "We have destroyed the whole of Iraqi society. We have killed hundreds of thousands of people with sanctions."
"We have used depleted uranium - and no one talks about the effects it has on the people we used it on, only the British veterans.
"We are still bombing and Saddam is still there."
Speaking ahead of an anti-sanctions demonstration due to be held outside parliament later on Tuesday, Mr Benn said that United Nations weapons inspectors had been sent into Iraq to help the west target future attacks.
"It really is the systematic destruction of a country for reasons I think are more connected with oil than human rights."
But Foreign Office Minister Peter Hain defended the sanctions saying that they had helped contain Iraq and prevent it destabilising the region.
He denied that the aim of sanctions was to bring the Iraqi dictator down, saying that if Saddam complied with weapons inspectors then sanctions could be lifted.
"The difference between us and the critics is they just want us to walk away, abandon sanctions, abandon our military efforts, allow him to invade Iran, allow him to invade Kuwait, as he repeated yesterday he would do.
"Allow him to lob missiles into Israel, allow him to use chemical weapons on the Kurds in the north.
"There's a kind of amnesia about Saddam's brutality in the region," Mr Hain said.
'Keep sanctions'
The Kuwaiti ambassador to London, Khaled Al Duwaisan, whose country was invaded by Iraq in 1990 thus prompting the 1991 Gulf War, urged the maintainance of sanctions.
He said that a decade after the Gulf War, the Iraqi leader remained a threat to the whole region.
"We still feel that his regime should be contained. We are sure that he has weapons of mass destruction."
Liberal Democrat foreign affairs spokesman Menzies Campbell said that Saddam remained "as much of a threat to the Middle East as ever".
"The strategy can only be containment backed up by the credible threat of military force. As part of that strategy military and dual-use sanctions must be maintained," he said.
"But there is no continuing case for non-military sanctions which have debilitated the Iraqi people without weakening Saddam Hussein.
"Ordinary Iraqis have paid the price of non-military sanctions while Saddam Hussein and his cronies have been unaffected and his regime of brutality has continued unabated."
Tuesday's anti-sanctions protest at Westminster is expected to see hundreds of demonstrators descending on parliament.
Campaigners from groups including CND and Reclaim the Streets want MPs to "account for their complicity in the suffering of the Iraqi people under sanctions".
The demonstration is expected to feature a samba band, puppets and the Cardiff Red Choir.
Organisers have warned that there will be "several direct action surprises".