Pakistani President Pervez Musharraf warned US troops would be regarded as invaders if they crossed into Pakistan to hunt al-Qaida militants and said he would resign if opposition parties tried to impeach him after next month's elections.

Musharraf's remarks in an interview with Singapore's The Straits Times published on Friday came as police investigated a suicide attack a day earlier in the eastern city of Lahore that killed 24 people, adding to pressures on the former general as he struggles to stay in office eight years after becoming president.

Pakistan is under growing US pressure to crack down on militants in its tribal regions close to the Afghan border.