By Amie Ferris-Rotman and Mirwais Harooni
KABUL (Reuters) - Taliban militants launched a large-scale attack involving the United Nations in the center of the Afghan capital Kabul on Friday, sparking a five-hour battle with security forces.
A plume of smoke hung over Kabul after the attack was launched, with the sound of .50 caliber heavy machine guns, rocket-propelled grenades and sniper fire clearly audible throughout the city center as night fell.
An Afghan police officer was killed and 10 other people were wounded during the attack, which began at 4 p.m. (1130 GMT) with a suicide car bomb outside a compound used by the International Organisation for Migration (IOM), Afghan police said.
While the IOM is not part of the United Nations, it is affiliated with it in Afghanistan.
The attack came eight days after six American soldiers and civilians and nine Afghans were killed in a suicide car bombing in Kabul.
The Taliban, fighting to expel Western forces and establish Islamist rule in Afghanistan, claimed responsibility for Friday's attack, saying a "rest house" used by the U.S. Central Intelligence Agency (CIA) had been attacked.
After the initial bombing, about six Taliban fighters engaged in a firefight with nearby guards, officials said.
Two were killed and the remaining three or four militants entered an unused building across the road from the IOM compound and continued to fight.
There were at least four large blasts during the course of the evening, and witnesses said that at 9 p.m. (1630 GMT) exchanges of fire were still going on between the attackers and Afghan forces supported by Norwegian special forces.
"As a result of the attack, three IOM staff and one International Labour Organisation (ILO) staff were wounded," U.N. spokesman Eduardo del Buey told reporters in New York.
He said one of the IOM personnel was in serious condition, and that all U.N. staff in Kabul had been accounted for.
The ILO is a subsidiary of the United Nations and operates in Kabul under the banner of the U.N. Assistance Mission in Afghanistan (UNAMA).
Such attacks reinforce concern about how the 352,000 members of the Afghan security forces will cope with the insurgency after most foreign NATO-led combat troops leave by the end of next year.
Insurgent attacks against civilians, government workers and Afghan security forces have increased since the Taliban announced their so-called spring offensive late last month.
A Taliban spokesman, Zabihullah Mujahid, speaking to Reuters by telephone, said Friday's attack had targeted a compound used by the CIA.
It is likely that the Taliban, driven from power in Kabul by a U.S-led force in late 2001, are using the high-profile attacks to exert increasing pressure on the Afghan government and their international backers.
Last year, more than a dozen people were killed during a Taliban attack in Kabul that started with coordinated suicide attacks and led to an 18-hour siege in the heart of the city.
(Additional reporting by Louis Charbonneau in New York; Writing by Dylan Welch; Editing by Kevin Liffey)