AFP/Kabul

At least 12 civilians were killed in twin roadside bomb blasts in Afghanistan, officials said Sunday, blaming the attacks on the Taliban as the militants intensify their summer offensive. 

A roadside bomb ripped through a passenger van on Saturday in Tagab district of Kapisa, an often restive province in the mountains east of the Afghan capital Kabul, killing 10 civilians and wounding six others, provincial officials said.

"A civilian van travelling from Kabul to Alasay district of Kapisa hit a roadside bomb planted by the Taliban," Qais Qaderi, a spokesman for the provincial governor, told AFP.

"Ten civilians, all men, were killed. Three children and three women were wounded," he said.

Abdul Karim Fayeq, the provincial police chief, confirmed the incident and blamed the Taliban for the blast.

No one has claimed responsiblity for the attack but roadside bombs have been the Taliban's weapon of choice in their war against foreign and Afghan security forces, now in its 14th year.

The bombs also increasingly kill and wound civilians.

Mohammad Hussain Sanjari, head of the provincial council of Kapisa, said the wounded civilians were taken to a local hospital for treatment.

In another incident, at least two civilians were killed and four civilians and two police were wounded when a police vehicle hit a roadside bomb in Kunduz city on Sunday, provincial police spokesman Sayed Sarwar Husseini told AFP.

The insurgents launched a countrywide offensive in late April, stepping up attacks on government and foreign targets in what is expected to be the bloodiest fighting season in a decade.

The Taliban, who promised to "safeguard" civilian lives during their offensive, are known to distance themselves from attacks that result in high civilian casualties.

The surge in insurgents attacks has taken a heavy toll on ordinary Afghans, according to the UN mission in Afghanistan.

Almost 1,000 civilians were killed during the first four months of this year, a sharp jump from the same period last year, the UN said.