A Chinese-born engineer was sentenced Monday to more than 15 years in prison for hoarding sensitive information about the US space shuttle with the intent on giving it to China.

U.S. District Judge Cormac J. Carney ruled that Dongfan Greg Chung, 74, of Orange, had spied for the Peoples Republic of China for more than 30 years.

The case represents the United States' first trial on economic espionage charges.

Chung, a former engineer for Boeing was convicted in July of six counts of economic espionage and other federal charges for keeping 300,000 pages of sensitive papers in his home.

Carney called Chung's crimes a matter of national security, saying he had committed a breach against the trust Boeing and the country had placed on him.

Chung's attorney had argued that his client passed along only publicly available information and should serve five years.

But what I do know is what he did, and what he did pass, hurt our national security and it hurt Boeing, the judge said.

The court said his scheme with China had started in 1970's. During brief remarks, Chung asked for leniency.

Your honour, I am not a spy, I am only an ordinary man, he said, adding that he had brought the Boeing documents home to write a book.

I love this country ...Your honour, I beg your pardon and let me live with my family peacefully.

Despite Chung's age, prosecutors requested a 20-year sentence, in part to send a message to other would-be spies.

Assistant U.S. Attorney Greg Staples noted in sentencing papers that Chung amassed a personal wealth of more than $3 million US while betraying his adopted country.

The [People's Republic of China] is bent on stealing sensitive information from the United States and shows no sign of relenting, Staples said. Only strong sentences offer any hope of dissuading others from helping the PRC get that technology.

Chung's attorney has said his client will appeal.

U.S. Engineer China