"The so-called accusations of Chinese espionage are unacceptable, groundless and done out of ulterior motives," foreign ministry spokeswoman Jiang Yu told journalists.
Jiang was responding to the sentence handed down to Tai Mak after he was found guilty by a California court of conspiring with his brother to pass sensitive submarine technology data to China.
US federal judge Cormac Carney said the harsh sentence was meant to send a message to China's intelligence services.
Tai Mak's brother, Chinese-American engineer Chi Mak, was found guilty of spying in May 2007 and sentenced last month to 24 years behind bars.
He was an engineer who worked for a US Navy contractor that develops the technology to silence submarines and was described as a Chinese "sleeper" agent during his trial.
Prosecutors said the information dealt with stealth submarine technology.
Tai's wife, Fuk Li, and his son, Billy, pleaded guilty in the case, and are expected to be sentenced in the coming weeks.
The charges date back to 2005, when police arrested Tai Mak and Fuk Li at Los Angeles airport as they prepared to leave for Hong Kong carrying a CD with the data in their baggage.
Billy was tasked with encrypting the information onto a CD-ROM before it was delivered to Chinese authorities.
Last Mod: 22 Nisan 2008, 17:44