KIKRUK, Iraq (AFP) - At least 18 people were killed in a suicide bombing, capping a week of horrific violence in Iraq as Al-Qaeda-linked militants threatened to kill two American and a British hostage in 48 hours.
More than 400 Iraqis have perished in a wave of bombings and fighting since the start of the month, exacerbating fears over the security situation four months before general elections are scheduled to be held in January.
In the latest attack, a suicide bomber smashed through the security barriers outside the Iraqi national guard headquarters in Kirkuk, in what was the second major attack on the fractured northern oil city in two weeks, police said.
At least 18 people were killed and another 63 people were wounded, hospital officials said.
The vehicle passed through three barriers before it reached the outer gate of the building and exploded, sending shrapnel flying into a crowd of national guard recruits lined up outside.
Ambulances raced to the site and police fired warning shots in the air, in scenes all too familiar in Iraq, where the health ministry reported at least 268 killed in the past week alone and another 820 wounded.
Meanwhile, loyalists of suspected Al-Qaeda operative Abu Musab al-Zarqawi threatened to kill two Americans and a Briton unless Iraqi women prisoners are freed within 48 hours, according to a videotape broadcast on Al-Jazeera television.
The US military said only two Iraqi women, both of them high-security detainees who are believed to have been instrumental in Saddam Hussein`s weapons programmes, are being held in the country.
Three blindfolded men were shown sitting in front of gunmen dressed entirely in black, pointing their guns at the pale-faced hostages.
Americans Jack Hensley and Eugene "Jack" Armstrong and British engineer Kenneth Bigley were abducted by gunmen from their Baghdad home on Thursday.
Zarqawi militants have previously claimed to have executed four foreign hostages, an American, a Turk, a South Korean and an Egyptian. Last month, they
released two Turks after the men`s firm agreed to stop supplying US forces in Iraq.
In further violence, five bodyguards for Mohammed Ahmed Zebari, a senior official at the oil ministry in Mosul, died in a hail of gun and rocket-propelled grenade fire in the northern city, said police. Zebari emerged unscathed from his car.
A child also died when a bomb exploded near his parents` home in the Shiite Muslim city of Hilla, medical sources said.
In Baquba, nine people were wounded by shrapnel when a mortar round struck a crowd of students and parents awaiting exam results outside a school, police and hospital sources said.
Again in the Kirkuk area, gunmen shot dead an Arab Shiite tribal leader.
Sheikh Khadem al-Hani was killed and two of his bodguards wounded when gunmen ambushed them from a black Opel car at 12:20 pm (0820 GMT) in Karadra, 25 kilometres (15 miles) north of Kirkuk, said local police chief Turhan Yusef.
Kirkuk, home to a mix of Kurds, Arabs and Turkmen, is a volatile place, haunted by the spectre of ethnic violence.
The body of Bassem Mohammed, deputy governor of Al-Anbar province, was found in an open field near Ramadi, the provincial capital, a police officer said. Mohammed had been kidnapped on September 8 by gunmen who stopped his car and wounded his son in the attack.
The murder was the latest in a string of setbacks in Al-Anbar, where the city of Fallujah has become a no-go zone for US troops.
British troops withdrew from the office of radical cleric Moqtada Sadr in the southern Iraqi city of Basra on Saturday after commandeering the building in overnight clashes that wounded eight people, officials said.
A Sadr aide had threatened to attack British troops occupying the building.
Despite the rampant unrest, which hardly sells Iraq as a tourism destination, national carrier Iraqi Airways launched its first international flight in 14 years, with a plane arriving in Baghdad from Amman -- albeit without any passengers.
The airline had been grounded since Iraq`s 1990 invasion of Kuwait and the subsequent UN sanctions imposed on the former regime of toppled dictator Saddam Hussein. It has only one functioning plane, a Boeing 737.
With death and destruction part of current daily life in Iraq, a London newspaper reported that British Prime Minister Tony Blair had been fully briefed on the risks of Iraq sliding into chaos if Saddam Hussein was removed from power.
"There seems to be a larger hole in this than anything," wrote Foreign Secretary Jack Straw in one of several secret documents that were shown to Blair a full year before the US-led invasion he so staunchly backed.