For more than ten years, international hackers had "widespread access" to the corporate computers of Nortel Networks, a report says.

The Wall Street Journal reported Tuesday that seven passwords used by the company's executives, including its CEO, were in the hands of cyberspies, most likely based out of China.

The hackers had access to the former technology giant's computers as far back as 2000, and downloaded technical papers, research and development reports and business plans, according to 19-year Nortel veteran Brian Shields, who headed a six-month investigation into the breach.

Shields told the Journal that the hackers had "plenty of time" and "access to everything" they wanted.

"All they had to do was figure out what they wanted," he said.

Nortel did not disclose the breach to potential buyers, the Journal reported.

The company filed for bankruptcy in 2009 and sold off its assets to a number of technology companies.

China's Washington embassy said there was no evidence presented in Shields' allegations to prove the hackers came from their country.

But experts say at any time, hundreds of attacks are being carried out from China.

"China has clearly understood cyberspace is as important to the information age as nuclear weapons were to the industrial age , and therefore they have developed a government strategy to operate in and through cyberspace," security expert Rafal Rohozinski of SecDev Group told CTV News.

However, experts say the scope of the problem is difficult to ascertain, as corporate victims rarely come forward.