When asked about the new report on Monday, a propaganda official in Sichuan’s capital, Chengdu, said “it’s ridiculous” to suggest that the Chinese government might have played a role. “The Chinese government considers hacking a cancer to the whole society,” said the official, Ye Lao. Tensions have risen between China and the United States this year after a statement by Google in January that it and dozens of other companies had been the victims of computer intrusions coming from China.

The spy operation appears to be different from the Internet intruders identified by Google and from a surveillance ring known as Ghostnet, also believed to be operating from China, which the Canadian researchers identified in March of last year. Ghostnet used computer servers based largely on the island of Hainan to steal documents from the Dalai Lama, the exiled Tibetan spiritual leader, and governments and corporations in more than 103 countries.

The Ghostnet investigation led the researchers to this second Internet spy operation, which is the subject of their new report, titled “Shadows in the Cloud: An investigation Into Cyberespionage 2.0.” The new report shows that the India-focused spy ring made extensive use of Internet services like Twitter, Google Groups, Blogspot, blog.com, Baidu Blogs and Yahoo! Mail to automate the control of computers once they had been infected.

The Canadian researchers cooperated in their investigation with a volunteer group of security experts in the United States at the Shadowserver Foundation, which focuses on Internet criminal activity.

“This would definitely rank in the sophisticated range,” said Steven Adair, a security research with the group. “While we don’t know exactly who’s behind it, we know they selected their targets with great care.”

By gaining access to the control servers used by the second cyber gang, the researchers observed the theft of a wide range of material, including classified documents from the Indian government and reports taken from Indian military analysts and corporations, as well as documents from agencies of the United Nations and other governments.

“We snuck around behind the backs of the attackers and picked their pockets,” said Ronald J. Deibert, a political scientist who is director of the Citizen Lab, a cybersecurity research group at the Munk School. “I’ve not seen anything remotely close to the depth and the sensitivity of the documents that we’ve recovered.”