Kabul. An Afghan border policeman has been killed and two Pakistani soldiers wounded in an exchange of fire along the border, officials from both countries have said.A senior Afghan official said hundreds of additional Afghan troops had been sent to a disputed border gate after the exchange of fire late on Wednesday, which lasted for more than two hours.A Pakistani military source said the shooting was triggered by an attack on a Pakistani checkpost."It was continuous fire on one of our checkposts that forced our troops to retaliate,” the official told the AFP news agency."[The] Afghan National Army was firing with small and heavy weapons. At least two of our security personnel were injured. We will raise this issue on the proper forum.”The senior Afghan official said trouble started after Pakistani troops attempted to fortify the border gate.An administrative official in the Mohmand district along the Afghan border confirmed the exchange of fire and told AFP that five ambulances had been sent to the area.