Los Angeles, Mar 25: A Chinese-born US engineer convicted of conspiring to smuggle sensitive technology about US Navy submarines to China has been sentenced to 24 years in jail, justice officials said.

Chi Mak, who worked for a US company with several Navy contracts, was convicted last May of trying to export intelligence about silent submarines in a plot that involved four members of his family.

Mak, whose age was given as 65 by justice officials, was also fined USD 50,000 yesterday by US district judge Cormac Carney, who said the lengthy sentence was intended to send a message to China's intelligence services.

"We will never know the full extent of the damage that Mr Mak has done to our national security," Carney wrote in a statement of reasons filed in conjunction with the sentencing.

"A high-end ... Sentence will provide a strong deterrent to the PRC (People's Republic of China) not to send its agents here to steal American military secrets." Mak was convicted following a trial in Santa Ana, 53 kilometres southeast of Los Angeles, last year. He was found guilty of two counts of attempting to send sensitive material to China, acting as a foreign agent without notifying the US government and making false statements to federal agents.

Mak was arrested in October 2005 after agents swooped on two relatives at Los Angeles airport as they prepared to board a flight to Hong Kong. Prosecutors said the duo were caught with a disk containing sensitive encrypted data on US submarines hidden in an English-language CD course.