A military court Thursday convicted a British air force doctor of disobeying orders and sentenced him to eight months in prison after he called the Iraq war illegal and refused to return for a third tour of duty.

Flight Lt. Malcolm Kendall-Smith, who said U.S. actions in Iraq were on par with those of Nazi Germany, was convicted by a panel of Royal Air Force officers, dismissed from the service and sentenced to prison after a three-day court-martial.

Kendall-Smith, 37, had served twice in southern Iraq but refused to return a third time in June because he said he was not prepared to take part in an "act of aggression."

He had pleaded innocent to five charges of failing to comply with a lawful order after refusing to deploy to the city of Basra last year.

Kendall-Smith's lawyer, Justin Hugheston-Roberts, said he planned to appeal.

Outside court, Hugheston-Roberts read a statement from Kendall-Smith in which the doctor said he had "two great loves in life — medicine and the Royal Air Force."

"To take the decision that I did caused me great sadness, but I felt that I had no other choice," the statement said.

Speaking on behalf of the air force, Wing Commander Ailsa Gough restated the Ministry of Defense's position that "the orders given to Flight Lt. Kendall-Smith were lawful and, therefore, should have been obeyed."

She said it would be inappropriate to comment further.

Kendall-Smith, a dual British-New Zealand citizen, could have received up to two years in detention.

He told the court he did not want to be complicit with an action contrary to international law.

"I have evidence that the Americans were on a par with Nazi Germany with its actions in the Persian Gulf," he said.

He did not specify which U.S. actions he believed were similar to those of the Nazis.

Kendall-Smith, who studied philosophy in New Zealand, refused to take part in training prior to his third deployment because he believed these were "preparatory acts which were equally criminal as the act itself."

The Pentagon says more than 5,500 U.S. servicemen have deserted since the war started in Iraq. It is unclear how many have challenged the legality of the war.

Kendall-Smith's lawyers had argued that since Iraq had not attacked Britain or one of its allies, there was no lawful reason to invade. The officer was entitled to disobey the "unlawful" orders, they said.

Prosecutor David Perry told the court that since May 2003, two months after the invasion, coalition forces in Iraq were operating under the authority of a U.N. Security Council mandate and at the invitation of Iraq's provisional government.