Bangkok - A Thai court on Thursday sentenced a woman with a history of mental disorders to eight years in jail, commuted to four, for stabbing four schoolgirls at a prestigious Bangkok private school in 2005.

The Bangkok Criminal Court found Jitrada Tantiwanichayasuk, 36, guilty of planning in advance a knife attack on four girls at Bangkok's St Joseph's School on September 9, 2005, that left at least one of the victims in critical condition although she later recovered.

Jitrada, who fled the scene of her crime on a motorcycle taxi, had a long history of mental illness and later told police that she had attacked the girl because they came from rich Chinese and Indian families who had exploited Thai people.

The Criminal Court threw out the defence's argument that Jitrada was mentally disturbed at the time of the crime, noting that she had deliberately planned the attack and had acknowledged she was doing wrong.

The court commuted the sentence from eight to four years in jail because Jitrada had confessed to the crime, and added that the defendant will be sent to hospital for medical treatment for her mental problems after serving her jail time.