PARIS (Reuters) - Carlos the Jackal, the master guerrilla who goes on trial on Friday in the 1975 slaying of two counter-espionage agents, intended to insult a prison guard when he called him a "gnu", a court ruled on Thursday. The opinion by a Paris administrative tribunal upheld a disciplinary sanction of a suspended 10 days in solitary confinement against the jailed international guerrilla, who contested the sanction. Carlos argued that he had not intended his 1996 remark as an insult. "Simple guard. You gnu, you! I am a free man and I have principles that I follow. No simple guard is going to stop me," he told the prison employee. The guard had refused Carlos' demand that he deliver a letter to the director of the La Sante prison in Paris. A gnu is an African antelope with curved horns, a mane and a beard. Carlos was sentenced to life in prison in absentia five years ago in the 1975 shooting in Paris of the French counter-intelligence officers and a Lebanese accomplice turned informer. A third French officer was wounded in the shooting. After his capture in 1994, Carlos demanded a new trial, to which anyone convicted in absentia is entitled under French law.