President Pervez Musharraf on Friday night said religious and sectarian extremists might "pull down" Pakistan.
"There is no external threat that can do any harm to us. We are capable of handling any external thereat. The enemy lies within..." he said at the annual dinner of the All-Pakistan Textile Mills Association in Islamabad.
His remarks came hours after seven Shias were killed and several injured when gunmen fired at their bus in Karachi.
The Lashkar-e-Jhangvi, a banned Sunni outfit, was thought to be behind the attack.
Their acts "impact on us internally and impact our reputation externally. That is the area that we have to guard against", the president said.
"We have been hijacked by unenlightened exponents of the religion. The vast majority is a silent majority is a silent majority. We will not allow this country to be used and misused by extremists."
The criticism also came a day before the arrival of US Deputy Secretary of State Richard Armitage and Assistant Secretary of State Christina Rocca.
"There will be no extremists in Pakistan. Pakistan is an Islamic country; it will remain an Islamic country and no law can be enacted here which is against the teachings of the Holy Qur'an and the Sunnah," he said.