An army lieutenant accused of raping a fellow soldier's 14-year-old daughter has been dishonourably discharged from the military.

The Defence Ministry ordered the dismissal of Lt Jarae Rojanasawinya of the 3rd Infantry Battalion, 5th Infantry Regiment, without a pension, finding him guilty of serious disciplinary violations and gross misconduct.

The family of a 14-year-old girl has accused the lieutenant of raping their daughter on several occasions and videotaping the abuse to blackmail the girl into silence.

The family has filed a complaint with police in Songkhla. The alleged rapes had occurred since March this year, Thai media reported.

The girl, daughter of a sergeant major first class in Songkhla, had reportedly suffered severe depression and tried twice to commit suicide.

The man denied raping the girl and in turn accused the girl's mother of twisting the facts to help her sergeant major husband, whom he accused of firing shots in a military camp and attempted murder. 

The sergeant major told the media that he fired shots into the ground to prevent the lieutenant from firing shots at him.

Both men were suspended from duty after the incident.