A political comeback by Sharif before parliamentary elections set for Jan. 8 would threaten the ruling party that supports Pakistani President Gen. Pervez Musharraf, who has declared a state of emergency.
Sharif traveled to the Saudi capital, Riyadh, on Thursday on a plane sent by the king, a spokesman for Sharif's party, Ahsan Iqbal, told The Associated Press.
"His return to the country is definite, but when I cannot tell you. This will be clear after his meeting with the king," Iqbal said Thursday.
Musharraf has insisted that Sharif, whose government he ousted in a 1999 coup, stay out of Pakistan until after the elections.
But speculation that Saudi Arabia may be willing to let him go home has been rife since Musharraf made a surprise trip to Riyadh for talks with King Abdullah on Tuesday.
Musharraf's spokesman, Rashid Qureshi, said Thursday that he had no information about any plan for Sharif to return to Pakistan.