Up to 35 military helicopters carrying troops landed in the small northwestern town of Bannu, about 40 km from the Afghan border on Wednesday afternoon, residents said.
Asked whether any operation against al-Qaida members was imminent, military spokesman Major General Shaukat Sultan replied, "As far as we are concerned these are part of routine training exercises the army conducts in various parts of the country." He said no foreign troops were involved.
But another security official, who did not want to be identified, said an operation might soon be launched against al-Qaida members thought to be hiding in the Waziristan tribal region bordering Afghanistan.
The reports of the troop movement came a day after Pakistan's Interior Minister Faisal Saleh Hayat said the noose was tightening around bin Ladin, prime suspect in the 9/11 attacks.
Thursday's edition of Pakistan's leading newspaper, The News, said the transportation of troops on Wednesday combined with Hayat's remarks had fuelled speculation that bin Ladin was hiding in the region, but it provided no source for the suggestion.
"As far as we are concerned these are part of routine training exercises the army conducts in various parts of the country"
Military Spokesman, Pakistan
Hamid Shah, a provincial assembly member of an Islamic party, reacted angrily to the presence of the troops in Bannu, saying they were there at the behest of the United States.
He said this went counter to Pakistani sovereignty and charged that the pro-military government had "mortgaged the country after 9/11 to America".
Hundreds of al Qaida suspects, including Khalid Sheikh Muhammad, the suspected mastermind of the 11 September attacks and Abu Zubaydah, one of bin Ladin's top aides, have been arrested in Pakistan since it joined the US-led "war on terror".