American computer analysts have traced more than 100 attacks on government departments, companies and journalists to the site of the 12-storey building about 40 minutes outside Shanghai's city centre.
A 60-page report by Mandiant, a computer security company, said the headquarters of People's Liberation Army Unit 61398 was located in the compound.
The Daily Telegraph confirmed that a woman who questioned a reporter's purpose in visiting the area was a member of Unit 61398. While she admitted her afilliation, she refused to produce any identification.
The Mandiant report said a hacking network named the Comment Crew or the 'Shanghai Group' operated from the compound. It said "hundreds, and perhaps thousands of people" were working inside to breach the security of global corporations, as well as foreign power grids, gas lines and waterworks.
While the Shanghai PLA base is off-limits to outsiders, the existence of the military compound is no secret in what is a bustling residential neighbourhood.