Yemeni officials say President Ali Abdullah Saleh has left the country to seek medical treatment in the United States while vowing to return to Yemen continue leading his ruling party.

The officials say Mr. Saleh flew out of the capital, Sana'a, on Sunday en route to Oman, where he would stay for a brief period before continuing his journey to the United States. Mr. Saleh was severely wounded in a bomb attack on his presidential compound last June and spent several months recuperating in Saudi Arabia. He has spoken previously of a desire to seek further treatment in the United States.

Yemeni state media say President Saleh gave a farewell speech to party officials earlier Sunday. The reports say Mr. Saleh asked the Yemeni people to forgive him for mistakes made during his 33-year autocratic rule. Yemeni opposition activists have staged a year of mass protests demanding his immediate ouster, inspired by popular uprisings in other parts of the region.

Thousands of Yemenis rallied in the capital Sana'a on Sunday, calling for Mr. Saleh to be put on trial for a violent crackdown on the uprising in which hundreds of people have been killed.

The anti-Saleh protesters reject a law that grants Mr. Saleh full immunity from prosecution. Yemen's parliament approved the law Saturday, as part of a Gulf Cooperation Council-backed plan to encourage the president to leave office. Mr. Saleh signed the plan last November and agreed to transfer presidential powers to his deputy ahead of the February election that will pick his successor.

Yemeni Vice President Abed Rabbo Mansour Hadi is the consensus candidate of Yemen's ruling party and parliamentary opposition for that election.

In Mr. Saleh's meeting with party officials, Yemeni state media say he declared Hadi to be responsible for the country and promoted the vice president to the military rank of field marshall.