Residents of the lawless Waziristan tribal region said they had noticed "abnormal movement of military convoys in the area" and this had caused fears of another showdown between the army and tribal militants affiliated with al-Qaeda, The Express Tribune reported.
The top military leadership cancelled holidays for the festival of Eid-ul-Fitr for troops deployed in the restive region and directed them to stay alert, the report said.
The preparations for a possible campaign against militants emerged as Gen James Mattis, commander of the US Central Command, held talks in Islamabad yesterday with Pakistan Army chief Gen Ashfaq Pervaiz Kayani and other top military officials.
Senior officials were quoted by the Tribune as saying that Mattis and Kayani would discuss how to eliminate their "common enemy" Tehrik-e-Taliban Pakistan chief Hakimullah Mehsud.
A statement issued today by the US Embassy said the two commanders had discussed common security issues, including steps to improve cross-border cooperation.
An operation in North Waziristan to eliminate the sanctuaries of the Haqqani network has been a longstanding demand of the US and is a key irritant in bilateral ties.
However, US officials have said that any drive in North Waziristan is expected to target the TTP and not the Haqqani network.