Foreign office spokeswoman Tasnim Aslam confirmed the visit but gave no immediate details.

"He is planning a visit but I don't have a precise date," Aslam said.

US and Pakistani media have said he is due to arrive Monday on a one-day visit and is expected to meet with President Pervez Musharraf and Prime Minister Shaukat Aziz, among other senior officials.

Boucher's visit to the key US ally will be his second to Islamabad within a month.

It follows intense pressure on Musharraf to crack down on Taliban and al-Qaeda militants allegedly holed up in Pakistan's troubled northwestern tribal belt bordering Afghanistan.

It also comes in the wake of a political crisis triggered by Musharraf's attempt to sack Pakistan's independent-minded chief justice Iftikhar Muhammad Chaudhry in March, which caused widespread protests.