Parts of the downed F-117 wreckage - including the left wing with the US Air Force insignia, the cockpit canopy, the ejection seat, the pilot's helmet and a radio - are exhibited at Belgrade's aviation museum, according to an AP report.

"I don't know what happened to the rest of the plane," said Zoran Milicevic, deputy director of the museum, according to the AP. "A lot of delegations visited us in the past, including the Chinese, Russians and Americans ... but no one showed any interest in taking any part of the jet."

Wang Yanan, an associate editor in chief at Aerospace Knowledge magazine, told the Global Times that the F-117 could hardly have inspired the development of the J-20, due to the design differences between the two generations of fighters. He added that it is worthless to take an interest in obsolete technology for developing more state-of-art technologies.

"Despite being dubbed a stealth fighter, the F-117 functioned as a bomber because of its low speed and limited air attacking abilities, while the J-20, more resembling the F-22, is designed to have a powerful air attacking capability with a fast flying speed," Wang said.

Responding to the accusations about China's stealing of new technologies, Wang conceded that, as a forerunner for new technologies, the US can only provide a reference point for other countries but will never leak any details about the technologies, leaving many countries to develop weapons on their own or buy them from another country.

The US has, in recent years, stepped up its offensive against what it calls "Chinese tech spying." The FBI increased its agents assigned to counter alleged Chinese espionage from 150 in 2001 to more than 350 in 2007, USA Today reported.

Separately, Noshir Gowadia, an Indian-born former B-2 bomber engineer convicted of helping China design a stealth cruise missile, was due to be sentenced in court today.

Li Daguang, a Beijing-based military analyst, told the Global Times that such accusations are groundless and originate from envy and wariness of China's technological advancements.

"China not only has the freedom to develop high-end technologies but also the capability to develop them independently," he said.