BANGKOK (Reuters) - The Thai army said it was searching for a military helicopter that went missing on Sunday in northern Thailand with five people on board, including a major general.

The UH-72 light helicopter disappeared from radar at around 10.30 a.m. (1130 ET) around 30 minutes into its flight, said Lieutenant General Somsak Ninbanjerdkun, Third Area Army commander overseeing Thailand's north.

Among those on board was Major General Nopporn Ruanchan, commander of the army's 4th Infantry Division, he said.

"The helicopter is still missing," junta spokesman Winthai Suvaree said on Sunday.

The helicopter was returning to its base in Phitsanuloke from a flood relief mission in the Pai district near the border with Myanmar, Somsak said.

(Reporting by Panarat Thegumpanat and Pairat Temphairojana; Writing by Simon Webb; Editing by Richard Balmforth)