MANILA, Philippines -- A US navy hospital ship will return to the country on Friday for a 17-day mission to treat an estimated 15,000 patients in the southern and central Philippines, a Philippine government official said Thursday.

The USNS Mercy will be stationed off Polloc Harbor in Cotabato City, Presidential Commission on the Visiting Forces Agreement Executive Director Edilberto Adan said, adding he would lead kick off rites there Friday with US Ambassador to Manila Kristie Kenney.

It will be the hospital ship's second visit to the country. In 2006, it treated 16,000 patients in the southwestern provinces of Tawi-Tawi, Sulu, and the Zamboanga peninsula, Adan, a retired Army general and former deputy chief of staff of the Armed Forces said in a phone interview.

This year's mission will run from May 31 to June 16 and will cover 37 sites. The ship is staffed with 300 health and construction personnel, and 600 officers and sailors, a statement from Adan's office said.

While in Polloc Harbor, the mission will treat 180 patients with cleft pallets and will hold 20 medical and civic missions in Cotabato City, and the provinces of North Cotabato, Shariff Kabunsuan, Maguindanao, Sultan Kudarat, and Lanao del Norte, the statement said.

Towards the latter part of its mission, the USNS Mercy will sail to Western Samar province, for the completion of five engineering projects, including the repair of the Calbayog City Health Center, and medical missions in the towns of Isidro, Santa Margarita, Gandara, and Calbayog, it said.

Adan said doctors from the Armed Forces of the Philippines (AFP) as well as non-government organizations would assist in the medical missions.

The USNS Mercy is on a five-month humanitarian mission to the Western Pacific and Southeast Asia that began last April, the statement said.