TORONTO — A vast electronic spying operation has infiltrated computers, and has stolen documents from hundreds of government and private offices around the world, including those of the Dalai Lama, Canadian researchers have concluded.

In a report to be issued this weekend — “Tracking ‘GhostNet’: Investigating a Cyber Espionage Network” — the researchers said the system was being controlled from computers based almost exclusively in China, but that they could not say conclusively that the Chinese government was involved.

The researchers, who are based at the Munk Center for International Studies at the University of Toronto, had been asked by the office of the Dalai Lama, the exiled Tibetan leader whom China regularly denounces, to examine its computers for signs of malicious software, or malware.

Their sleuthing opened a window into a broader operation that, in less than two years, has infiltrated at least 1,295 computers in 103 countries, including many belonging to embassies, foreign ministries and other government offices, as well as the Dalai Lama’s Tibetan exile centers in India, Brussels, London and New York.

The researchers said they believed that in addition to spying on the Dalai Lama, the system, which they called GhostNet, was focused on the governments of South Asian and Southeast Asian countries.

Intelligence analysts say many governments, including those of China, Russia and the United States, and other parties use sophisticated computer programs to covertly gather information.

The newly reported spying operation is by far the largest to come to light in terms of countries affected. The malware is remarkable both for its sweep — in computer jargon, it has not been merely “phishing” for random consumers’ information, but “whaling” for particular important targets — and for its Big Brother-style capacities. It can, for example, turn on the camera and audio-recording functions of an infected computer, enabling monitors to see and hear what goes on in a room.

The electronic spy game has had at least some real-world impact, they said. For example, they said, after an e-mail invitation was sent by the Dalai Lama’s office to a foreign diplomat, the Chinese government made a call to the diplomat discouraging a visit.