London: British Foreign Secretary Jack Straw has warned as US and British troops advance on Baghdad they will face fierce resistance and could experience setbacks.

"There may be more setbacks for coalition troops," Straw said in a speech to the Newspaper Society annual conference.

"As the regime enters its final stages, we will encounter fierce resistance from those elements of the regime's apparatus of terror whose fate is tied to their tyrannical ruler," he said.

Straw said Iraqi President Saddam Hussein had to be removed from power, as he was a "scar on the conscience of the world".

"We will rid the world of a brutal dictator, and, in doing so, ensure that the long- suffering Iraqi people will emerge from the shadow of dictatorship into the light of freedom," he said.

He said in the post-Saddam period, turning Iraq into a well off, Democratic nation would take "years".

Straw said a UN-led conference might be needed to bring together Iraq's ethnic and religious groups – its Kurds, Shiites and Sunnis, to form a new state after the war.

He said it was "increasingly probable" that Iraq was behind the attack on a civilian target in Baghdad last month.

"It's increasingly probable that this was the result of Iraqi, not coalition action," Straw said.

He was apparently referring to an attack on March 26 in Baghdad, in which 14 civilians were killed and around 30 wounded as two missiles fell in a working-class market district.

Straw warned people against making "snap judgments on the basis of television pictures".

He said a factor making people oppose the war might be that unlike Yugoslav dictator Slobodan Milosevic.

"Saddam Hussein has conducted his reign of terror off-camera, so unlike Kosovo, Iraq has not pricked the world's conscience through our televisions screens," Straw said.

"Saddam has waged a war, but a hidden one, against the Iraqi people.

"There are no TV cameras in Saddam's torture chambers or in the darkest corners of Baghdad. But the suffering and oppression are real.

"Until his long reign of terror is ended, Saddam Hussein will remain a standing affront to the ideals which underpin the foreign policies of the UK, the United States and our European allies," he said.

Concerning the market bombing, British Defense Secretary Geoff Hoon has said the attack may have been caused by the Iraqi military.

"Although investigations continue into this tragic incident, it could clearly have been caused by fallout from the regime's anti-aircraft fire or the failure of one of the regime's own missiles," Hoon said.

Baghdad has said allied fire was responsible.

The United States acknowledged it might have killed some civilians with air strikes.

A statement by the US Central Command said coalition warplanes used precision-guided weapons to attack nine Iraqi surface-to-surface missiles and launchers that were placed in a residential neighborhood of Baghdad.

"Most of the missiles were positioned less than 300 feet (90 metres) from homes," the statement said.

It made no direct mention of deaths in the text, but the headline read, "civilian damage possible".