Some of the peace activists who went to Iraq to serve as human shields in the event of war returned home, fearing for their safety, a spokesman said Sunday.

The human shields are mostly European activists who drove from London to Baghdad in two double-decker buses last month, intending to guard civilian sites from a U.S.-led military attack.

Those who returned home had safety or financial concerns, spokesman Christiaan Briggs said.

"The aim was always a mass migration and if we had had five to ten thousand people here there would never be a war," he said. "We do not have those numbers."

The Sunday Telegraph newspaper reported that nine of the 11 British human shields in the bus convoy had left Baghdad. Briggs said about a dozen Britons remained in Iraq alongside several dozens from other countries.

He told Britain's Press Association news agency that Iraq limited the sites that human shields could visit. "Now we are being told we cannot go to certain sites, such as hospitals, so we are reassessing our strategy," he said.

U.S. officials have said that it is a war crime to use civilians as human shields and that there's no way of guaranteeing their safety.

On Friday, the head of Sweden's largest peace organization urged human shields to leave Iraq, saying they were being used for propaganda purposes by Saddam Hussein.

Maria Ermanno, chairwoman of the Swedish Peace and Arbitration Society, cited reports that Iraqi officials were arranging transportation, accommodations and news conferences for the human shields.

"To go down to Iraq and live and act there on the regime's expense, then you're supporting a terrible dictator. I think that method is entirely wrong," Ermanno told Swedish Radio.