Meanwhile, Pakistani Interior Minister Aftab Khan Sherpao confirmed reports of an explosion at a Shi'ite mosque in a congested area of Peshawar, the capital of Pakistan's North West Frontier Province. No details were immediately available on the blast.
Pelosi's visit comes amid concerns in Islamabad over a provision in a U.S. bill that could cut off assistance to Pakistan's military if that country fails to stop the Taliban from operating from its territory.
Under the provision, U.S. President George W. Bush has to certify to Congress that Pakistan is doing its utmost to counter Taliban operations on its soil before new military assistance can be released.
The Bush administration believes setting conditions for aid to Pakistan could undermine counterterrorism cooperation and is trying to persuade Congress to drop the provision before it becomes law.
The bill was part of a raft of legislation introduced after Democrats took control of Congress in January. The House of Representatives has already endorsed it, while the Senate has yet to consider it.
Senior Afghan officials have repeatedly accused their Pakistani counterparts of doing too little to pursue terrorists and cross-border insurgents, and have even accused Pakistani elements of providing assistance to such militants.
Pelosi led a seven-member delegation to Iraq on January 26, where she met with Iraqi Prime Minister Nuri al-Maliki and with top U.S. officials. She reportedly told al-Maliki that the delegation thinks "it is well past time for the Iraqis to take primary responsibility for the security of their nation."
Some observers suggest the visits are an sign that the Democratically controlled U.S. Congress is seeking to stake out a more prominent role in shaping U.S. foreign policy.