WASHINGTON — Yemen’s outgoing president has left the U.S. after more than three weeks of medical treatment.

U.S. officials say Ali Abdullah Saleh (AH’-lee ahb-DUH’-luh sah-LEH’) departed Boston late Wednesday for Addis Ababa, Ethiopia.

They said they didn’t know his future plans. Saleh has pledged to return to Yemen for his successor’s inauguration.

Officials spoke on condition of anonymity because they weren’t authorized to talk publicly about Saleh’s travel plans. An Arab diplomat confirmed Saleh’s departure.

Saleh’s 33-year rule is coming to an end. Yemenis installed Vice President Abed Rabbo Mansour Hadi Tuesday in a single-candidate referendum. He’s expected to be inaugurated soon. That will make Saleh the fourth Arab Spring leader to be pushed from power.

The 69-year-old Saleh had been receiving treatment for wounds suffered in a June assassination attempt.