Pakistan says it has completed work on the first section of a controversial fence on the Afghan border aimed at restricting Taleban militants.
Pakistani troops where the fence has been completed
Afghan and Nato troops in Afghanistan have repeatedly complained of attacks from across the border.
Reports say more than 1,000 people have died in militant attacks in Afghanistan this year.
The Afghan government has expressed doubts that the fence will be effective and disputes its positioning.
"We have completed 20 kilometres (12 miles) of fencing in North Waziristan's Lwara Mandi area," army spokesman Maj-Gen Waheed Arshad told the AFP news agency.
The border is notoriously difficult to patrol
"This is the difficult part where most militants reportedly were crossing over."
On 19 April, Afghan and Pakistani troops clashed briefly when the Afghans destroyed a part of another section of the fence being erected between the Shkin and Barmal areas along the border in South Waziristan.
The 15-kilometre fence on this stretch would also be completed soon, Gen Arshad said.
Pakistani President Pervez Musharraf announced plans to fence parts of the border in February following pressure from Nato forces to crack down on militants who allegedly shelter in Pakistan.
The Afghan government disputes the border which was drawn up by colonial Britain in 1893 and has been strongly opposed to the fencing plan.
It argues that the fence would make the border, which it says cuts off some its territory, a permanent boundary.
It says it has begun diplomatic efforts to stop Pakistan from fencing the border.
It has also written to United Nations Secretary General Ban Ki-moon to express "deep concern".
The BBC's Ilyas Khan in Karachi says that few observers in Pakistan and Afghanistan expect the fence to stop cross-border movement by Taleban fighters.
But the measures might help ease pressure on Pakistan from the US, Nato and the UN who want it to do more to curb militant attacks in Afghanistan, they say.