A helicopter of U.S. Marine Corps was forced into emergency landing during a joint military exercise in central province of Phitsanulok on Wednesday, leaving one crew slightly injured.

Six others on board are safe after the CH-46 Sea Knight helicopter landed at the border of Phitsanulok's Nakhon thai district and Khao Kho district of Phetchabun province.

Lt Col.Ittipon Panphon, head of public relations of the "Cobra Gold 2013" training, told Matichon online that there were no Thai citizen on board.

Cobra Gold is an annual multinational exercise opened in Thailand on Febuary 11 with the participating of an estimated 13, 000 servicemen from the U.S., the host country Thailand and several other Asian nations.

The multinational military exercise, the biggest of its kind in the Asia-Pacific region, were held in the northern provinces of Pitsanulok and Sukhothai, the eastern seaboard provinces of Chonburi and Chantaburi and the central province of Lopburi.

The exercise is due to end this Friday.