The latest attacks come just days after the Afghan Taliban leader urged his fighters to avoid civilian casualties [AFP]

At least 11 people have been killed by a roadside bomb in northwest Afghanistan, sources say.

Two officers and eight civilians were among those killed after the blast struck a police vehicle and another car behind it in Badghis province late on Monday, Faizullah Azimi, the province's council chairman, said.

"A mine planted by the Taliban hit a police vehicle in Qadis district yesterday evening leaving two policemen and eight civilians dead," Azimi told the AFP news agency. "All the civilians were members of the same family."

"Two policemen and one child were also injured."

Monday was the second day of the Muslim holiday Eid al-Adha, when many Afghans celebrate by visiting friends and family.

It was the fourth attack during Eid in Afghanistan. On Sunday, a Taliban suicide bomber killed seven people returning from prayers at a mosque in Baghlan in northern Afghanistan.

The Taliban's spokesman was not immediately reachable to comment on the latest attack.

It came just days after Mullah Omar, the Afghan Taliban leader, urged his fighters to avoid civilian casualties in the decade-long Afghan war.

The Taliban published a statement on Friday on their website attributed to Mullah Omar, calling on fighters "to take every step to protect the lives and wealth of ordinary people".

The statement, issued to mark Eid al-Adha, warned of punishments under Islamic Sharia law for fighters responsible for civilian deaths.

The UN says the number of civilians killed in the Afghan war in the first half of this year rose 15 percent to 1,462, with anti-government fighters behind 80 percent of the deaths.

Around 140,000 international troops, mostly from the US, are serving in Afghanistan, helping government forces fight a bloody, Taliban-led armed campaign.

Limited withdrawals of foreign troops have already started, and all combat forces are due to leave by the end of 2014, although a sizeable training and mentoring mission is expected to remain.