The militiamen, hired by the Nato-led International Security Assistance Force (Isaf) to help with security, were killed Wednesday in southern Uruzgan province's Taliban-dominated Charchino district, Afghan general Rahmatullah Raufi said.

Taliban spokesman Yousuf Ahmadi called AFP from an unknown location and said that the landmine was planted by Taliban rebels.

"We had put the mine to target the foreign and Afghan troops. It was detonated by a remote control device," Ahmadi, who often calls media to claim attacks on behalf of the Islamist Taliban, told AFP.

Taliban loyalists have been waging violence against President Hamid Karzai's US-backed government and tens of thousands of Western troops hunting the militants down.

Afghan officials, including Karzai, have alleged that militants are crossing the border from Pakistan to carry out such attacks.

Pakistan's Prime Minister Shaukat Aziz arrived Thursday in Kabul to hold talks with the Afghan government amid a new row over the proposed fencing and mining of the two countries' joint border by Pakistan.

Some 4,000 people -- including 1,000 civilians, but mostly rebels -- died last year in insurgency-related unrest.

Meanwhile, Afghan and foreign troops killed 20 rebels, including two commanders, in operations against militants in southern Afghanistan, officials said Wednesday.

Seventeen, including the commanders, were killed in the southern province of Helmand in a three-day operation that wrapped up Monday and involved Afghan and Nato-led troops, interior ministry spokesman Zemarai Bashary told AFP.

About 4,500 British troops are in Helmand serving with Nato's International Security Assistance Force (Isaf).

An Isaf spokesman in the capital, Kabul, confirmed there had been "sporadic incidents" in the area, but could not confirm the interior ministry's death toll.

Provincial police chief, general Mohammad Nabi Mullahkhail, said two Taliban pickup trucks were destroyed in the operation in and around the province's Kajaki district.

British troops make up the second-largest contingent in the 37-nation Isaf, after the United States.

The separate US-led coalition focused on counterterrorism operations said its troops had called in an air strike on Monday against insurgents seen planting improvised bombs in Uruzgan province, also in the south.

Three were killed, it said. Uruzgan is the base of most of the 2,200 Dutch troops in Isaf.

The onset of winter has seen a drop in Taliban-linked violence, which soared to new heights last year. Most of the unrest was in the south, the heartland of the militia that was in government from 1996 to 2001.

The fighting killed about 4,000 people in 2006 -- most of them rebels.

Isaf said Wednesday that the past year had been difficult, but the force had ended it on a strong note.

"No one is pretending it has been an easy year," spokesman Mark Laity told reporters. "We have had many difficulties, many challenges. But we have ended the year strongly and successfully."

"The insurgency has had a very, very bad year," Laity said, adding: "If they launch the same kind of attacks this year as they did last year, the same thing will happen, which is they will take very, very heavy casualties."