A suicide bomber on a motorbike killed two people and wounded more than 35 in Kabul on Wednesday and foreign troops suffered their bloodiest day this year with five deaths in different attacks around the country.

Violence is at its worst since U.S.-backed Afghan forces overthrew the hardline Islamist Taliban in 2001 after they refused to hand over al Qaeda militants, including Osama bin Laden, after the September 11 attacks on the United States.

While attacks in the capital had been relatively rare in the past year, particularly since a ring of steel was erected in the city before a parliamentary election in September, the bombing on Wednesday was the third attack in less than a month.

Four foreign service members were killed in two separate attacks in eastern Afghanistan, while another was killed by a bomb in the south, the NATO-led International Security Assistance Force (ISAF) said. It gave no other details.

The suicide bomber in Kabul attacked a minibus carrying Afghan intelligence personnel in a western district of the city near the country's parliament, said Mohammad Zahir, head of Kabul's crime investigation unit.

Zahir said an intelligence official and a civilian had been killed and up to 36 people were wounded, most of them civilians.

Some of the wounded are in critical condition and the death toll may rise, Zahir told Reuters.

Taliban spokesman Zabihullah Mujahid told Reuters by phone from an undisclosed location his group carried out the attack.

Reuters television footage showed the wreckage of the minibus as Afghan soldiers stood guard.

I heard a huge bang and hid under my chair, said Sayed Khalil, a shopkeeper whose windows were shattered in the blast. After a few minutes, I rushed out to see what had happened and I saw two motorbikes on fire and two wounded people.

INHUMANE

The attack came a day after U.S. Vice President Joe Biden visited Afghanistan where he said the Taliban's momentum has been largely arrested, echoing findings of a strategy review by U.S. President Barack Obama last month.

Afghan President Hamid Karzai condemned Wednesday's bomb attack as inhumane and un-Islamic.

Violence has surged in Afghanistan with record casualties on all sides and a recent string of attacks around the country helping to dispel a belief that winter brings a lull.

Military commanders now speak less of fighting seasons and say they aim to pressure militants throughout the year. Insurgents have also vowed to continue fighting, and foreign commanders acknowledge militant attacks are up on a year ago.

A record 711 foreign troops were killed in 2010, according to monitoring website www.iCasualties.org.

Afghan forces have been hit even harder. The government has said 1,292 Afghan police, 821 Afghan soldiers and 5,225 insurgents were killed. It had not have the 2009 tolls.

But Afghan civilians have borne the brunt of the war. The United Nations has said 2,412 civilians were killed and 3,803 wounded between January and October last year -- up 20 percent from 2009.

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