KABUL (AFP) - A Taleban suicide attacker struck a government bus in Kabul on Monday, killing one civilian and wounding 15 others, officials said, as insurgent representatives hold talks with an Afghan delegation aimed at ending the country's 13-year war.

The bus was carrying employees of the attorney-general's office to work in downtown Kabul when the bomber struck, as the militants press on with their annual spring offensive.

"Our initial reports show a suicide attacker on foot targeted the attorney general's shuttle bus, wounding eight people, all civilians," interior ministry deputy spokesman Najeeb Danish told AFP.

The explosion blew out the windows of houses and shops nearby, Mr Ahmad Reshad, a government employee who was near the blast site, told AFP.

The Afghan Interior Ministry "strongly condemned" the attack, confirming that one civilian was killed and 15 others were wounded.

"These attacks... demonstrate [an] extreme level of atrocity by terrorists against innocent and defenseless civilians," the ministry said in a statement.

The attack comes after a 20-member Afghan delegation on Sunday launched two-days of "open discussion" with Taleban representatives in the Gulf emirate of Qatar - in their latest effort to end Afghanistan's long war.

The Taleban claimed responsibility for Monday's attack on their Twitter account, claiming that 40 people were killed or wounded.

The Taleban is known to exaggerate and distort its public statements as part of a propaganda campaign accompanying its campaign against Afghan and US-led foreign forces who ousted it from power in 2001.

Scores of shuttle buses take government and military personnel to work every morning in the capital, and they have often been targeted by insurgents despite efforts by security forces to provide better protection.

This year's Taleban offensive marks the first fighting season in which Afghan forces will battle the insurgents without the full support of US-led foreign combat troops.

Nato's combat mission formally ended in December, but a small follow-up foreign force has stayed on to train and support local security personnel.

The Taleban launched their spring offensive across Afghanistan late last month, stepping up attacks on government and foreign targets and inflicting a heavy toll on civilians and Afghan security forces.

The number of civilians killed and wounded jumped 22 percent in 2014 compared to the previous year, according to the United Nations Assistance Mission in Afghanistan (UNAMA).

And in the first three months of 2015, civilian casualties from ground fighting were up 8 per cent on the same period last year, a new UNAMA report said.