ALDERSHOT (Reuters) - A British Air Force doctor being court-martialled for refusing a posting to Iraq said on Wednesday he believed the United States was the moral equivalent of Nazi Germany.

Australian-born Flight Lieutenant Malcolm Kendall-Smith could face an unlimited jail sentence for disobeying an order to go to Iraq last year and four orders to prepare for his deployment.

The case is the first of its kind in Britain over the war in Iraq.

"As early as 2004 I regarded the United States to be on par with Nazi Germany as regards its activities in the Gulf," Kendall-Smith told the court amid a series of bitter exchanges with prosecutor David Perry.

Perry asked: "Are you saying the U.S. is the moral equivalent of the Third Reich?"

Kendall-Smith replied: "That's correct."

The judge in the case has already ruled that orders for British troops to deploy to Iraq in 2005 were legal because the British presence was covered by a United Nations Security Council resolution passed after the fall of Saddam Hussein.

Speaking firmly but often emotionally, Kendall-Smith testified in his own defense as the only witness called in the case. He said he initially tried to resign on learning he was being sent to Iraq, but later concluded it was his duty to remain in the Air Force and refuse the order.

"I love the Air Force today as much as the day I volunteered, sir," he said.

The case, before a civilian judge advocate and a panel of five officers, concluded on Wednesday, and the panel will return on Thursday to consider a verdict.

The judge provided no room for the panel to accept Kendall-Smith's argument that the orders were illegal.

"My direction to you, gentlemen, as a matter of law, is that each of the orders was a lawful order," judge advocate Jack Bayliss said. "The defense contention that the orders were unlawful is wrong."

Kendall-Smith's lawyers have conceded that Kendall-Smith did not obey orders. But they presented him as a conscientious officer trying to carry out his duty.

"All I ask you to think about is that he is a human being, and he has wrestled with his conscience, and has taken a great moral stride," his lawyer, Philip Sapsford, told the panel.

Prosecutors described Kendall-Smith, who holds both British and New Zealand citizenship, as an aggrieved officer who had repeatedly clashed with his superiors.

Kendall-Smith's belligerent testimony showed he was "an easily moved, stubborn individual, prone to displays of temper and resentment," prosecutor Perry said. "(He) would have been difficult for any senior officer to deal with."