BASRA, Iraq (AFP) - Hundreds of British soldiers left southern Iraq on a risky mission closer to Baghdad to free up US forces for a possible assault on rebel-held Fallujah, as Tokyo stood firm after militants threatened to behead a Japanese hostage.
A top Iraqi science official, meanwhile, said it was impossible that 350 tonnes of high explosives could have been smuggled out of a military site in Iraq before last year`s invasion, adding fuel to a scandal clouding US President George W. Bush`s election campaign.
Prime Minister Iyad Allawi has warned of escalating violence in the runup to elections in Iraq promised by January, but has pledged to restore stability -- by force if necessary.
To this end, Britain agreed last week to a controversial US request to move 850 crack troops from the southern city of Basra to the restive province of Babil, just south of Baghdad, as US soldiers focus on wresting the restive hub of Fallujah from rebel control.
"The convoy has begun to leave," said a British army spokesman.
The redeployment marks the first time since the March 2003 invasion of Iraq that British troops have left southern Iraq for US-controlled areas, where they are considered more likely to come under hostile fire.
Scores of tanks on transporters, along with other army vehicles, formed several convoys accompanied by US vehicles.
Helicopters were seen buzzing overhead as the battle group, led by the Black Watch battalion, rumbled northwards for a limited deployment, though Britain`s Prime Minister Tony Blair left open the possibility that other British troops may have to replace them.
"The Black Watch will come back by Christmas. As to what then happens, we can`t be sure at the moment," he said.
"We don`t believe that there will be a further requirement for our troops but I can`t commit myself, I can`t guarantee that," Blair told parliament in London.
The British deployment closer to Baghdad includes up to 550 Black Watch soldiers, coupled with specialists from other units, including engineering and communications.
The move came amid uncertainty over the fate of British-Iraqi aid director Margaret Hassan who was kidnapped on October 19 in Baghdad.
A tearful Hassan, 59, was last seen on a videotape broadcast by Al-Jazeera television last Friday, pleading with Britons to urge London against the redeployment of British soldiers.
Outgunned militarily, insurgents in Iraq use foreign hostages as political pawns to undermine the interim government and US-led military coalition.
In a parallel hostage drama, Japan insisted it would not bow to the demands of a militant group linked to Iraq`s most wanted man, Abu Mussab al-Zarqawi, that threatened late Tuesday to behead a 24-year-old Japanese traveller unless Tokyo withdrew its 600 or so troops within two days.
"The Self-Defence Forces will not withdraw," said Prime Minister Junichiro Koizumi, a staunch US ally. "We must not bow to terrorism."
The Al-Qaeda- affiliated group paraded Shosei Koda, a shaggy-haired man in a white T-shirt, at the foot of three armed and masked men in a video released on the Internet on Tuesday.
"We are giving the Japanese government 48 hours in which to withdraw its troops from Iraq, otherwise this infidel will join the others (executed)," a militant said.
Among the "others", the militants mentioned the American Nicholas Berg and Briton Kenneth Bigley, who were both executed by Zarqawi loyalists.
Zarqawi followers have claimed responsibility for some of the worst killings and kidnappings in Iraq, including Saturday`s massacre of 49 new soldiers and three drivers as they travelled home, unarmed, from a training course near the Iranian border.
More than 560 people have been killed and 1,200 wounded in 92 suicide attacks in the four months between June and September, according to Iraqi figures, and Allawi warned on Tuesday that worse was to come.
"Our enemies have realised that it would be a big blow to them if Iraq was stable and was on the right path, so they will escalate terror and criminal acts," he said.
Desperate to beat the insurgency, US and Iraqi forces have set their sights on wresting back control of Fallujah -- believed to be a Zarqawi operating base -- ahead of the elections.
A joint US-Iraqi force of about 1,000 has surrounded the city for some two weeks as US warplanes pound suspected Zarqawi hideouts almost daily.
Meanwhile, a top science ministry official, Mohammed al-Sharaa, countered claims by some members of the US administration that a vast amount of explosives went missing before Saddam Hussein was toppled in April 2003.
"It is impossible that these materials could have been taken from this site before the regime`s fall," he said, warning that other sites with similar materials could have also been plundered.
Elsewhere, a US soldier was killed and another wounded in a suspected motorcycle bombing Wednesday against their convoy in eastern Iraq, the military said.
And three Iraqis were injured by a car bomb along a road northeast of Baghdad that is often used by US military convoys.
Allawi has called on the United Nations to send troops to help with security for the elections, while lamenting a lack of Iraqi police.
The process of registering voters as well as political parties and candidates for the vote is due to begin on November 1 and Iraqi newspapers on Wednesday displayed large advertisments to raise awareness about the polls.
Separately, the top UN official in Iraq, Ashraf Jehangir Qazi, held talks with an influential group of Sunni Muslim leaders who have threatened to boycott the elections in the event of a military assault on Fallujah.

10/28/2004 - 00:45 GMT - AFP