Bagram, Afghanistan ? British troops have deployed near the Pakistani border to stop al-Qaida and Taliban fighters who may try to re-enter Afghanistan, officials said Wednesday.

In Operation Buzzard, British forces will conduct patrols in populated and rural areas by helicopter, foot and vehicle in a mission that will last longer than previous sweeps in the region, said Lt. Col. Ben Curry, a British spokesman.

Some 300 British troops have deployed over the past three days in the area, but a senior British official said the number could go up to 700.

“The key point is being unpredictable, operating overtly and covertly to introduce doubts in the minds of the al-Qaida and Taliban,” Curry said, adding that the operation will last “a couple of weeks.”

U.S. Maj. Bryan Hilferty said the mission is “to interdict al-Qaida and Taliban and infiltration routes and safe havens, to deny their freedom of maneuver, deny them sanctuary and gather intelligence.”

The operation is being launched at a time that coalition officials warn that al-Qaida and Taliban may launch insurgency attacks, including suicide bombings, to disrupt the June 10-15 meeting by the loya jirga, or grand council, to choose a transitional government.

The British troops are operating in plains south and east of the city of Khost near the Pakistani border, a sharp contrast to the rough mountainous regions where past British sweeps have taken place. The area is a key region for border crossings.

U.S. and Afghan officials say they have no information about specific threats, but there have been recent reports about possible attacks on Kabul, where 1,051 representatives from across the country will meet in two weeks to replace the transitional government installed by the United Nations in December.

In addition, the U.N. said Tuesday it was “deeply disturbed” at reports that participants in the loya jirga process are being intimidated, threatened and even detained in western Herat province. Eight other Afghans associated with the runup to the meeting have been killed this month. U.N. officials emphasized they had no direct evidence linking the deaths with the selection process.

Two former high-ranking Taliban officials told The Associated Press last week that the Afghan-Pakistan border can’t be sealed to stop the movement of militants. They said the Taliban’s supreme leader, Mullah Mohammed Omar, is overseeing a reorganization of the religious movement and has been in contact with Taliban warriors in their mountain hide-outs in Afghanistan.