Thirteen people have died in two attacks in Afghanistan's southern Helmand province.

In the first, a suicide bomber on a motorcycle killed seven civilians and two police officers in a bazaar in Kajaki district.

Nato said some of its personnel are among the wounded.

In a second attack, claimed by the Taliban, a roadside bomb killed a local intelligence official and at least two others in Nad-e-Ali district.

The bomb hit the vehicle in which the National Department of Security (NDS) chief Wali Mohammad was travelling, Afghan intelligence and police officials in Nad-e-Ali district told the BBC.

It killed him and two of his friends, including an influential tribal elder, the officials said. Three other people were injured.

The BBC's Bilal Sarwary in Kabul says Wali Mohammad was considered one of the most effective officials in the area.

Both he and the tribal elder who was killed with him were considered crucial in bringing Taliban fighters and commanders into the government, he adds.

About the first blast, a local intelligence official in Kajaki told the BBC: ''The bomber attacked a police patrol in a crowded area... Some of those injured are in a critical condition.''

No group has said it carried out the attack.

Gen John Allen, commander of Nato's International Security Assistance Force (Isaf), said in a statement that its personnel were among those wounded in the "brutal" attack.

"These attacks against the people of Afghanistan have no effect on the progress we are together making here with our Afghan partners and will only further isolate the Taliban from the process of peace negotiation," he said.