BEIJING, China - China insisted on Thursday it was opposed to Internet crimes, following a US media report that said Chinese hackers may have been behind a cyber attack on computers linked to a new US fighter jet.

"Some people keep making up stories, I don't know what their intentions are," foreign ministry spokeswoman Jiang Yu said.

"We resolutely oppose and crackdown on cyber crimes, including hacking."

Jiang was commenting on a Wall Street Journal report that computer spies hacked into the Pentagon's 300-billion-dollar Joint Strike Fighter project.

The newspaper cited unnamed former US officials as saying the attack appeared to have originated in China, which the Pentagon says has put a priority on bolstering its cyber-warfare capability.

Hackers may have attacked computer networks at contractors helping to build the new fighter jet, also known as the F-35, the paper said.

Despite the computer break-in, a Defence Department official said sensitive technology for the Joint Strike Fighter aircraft had not been compromised.

The Wall Street Journal report was the latest in a series of accusations emanating from the United States recently that have warned of an escalating Chinese cyber hacking threat. China has denied all such reports.