China on Tuesday refuted a claim that Chengdu-based hackers stole information from the Indian Defense Ministry.

"China firmly opposes any kind of cyber crime, including cyber attacks. The cyber attack is an international issue requiring the cooperation and joint efforts of the international community," Foreign Ministry spokesperson Jiang Yu told a press conference.

A group of researchers at the Munk Centre for International Studies at the University of Toronto claimed that a cyber-espionage group based in southwest China stole documents from the Indian Defence Ministry and emails from the Dalai Lama's office, the Telegraph reported. The hackers allegedly stole classified reports about security in several Indian states, and about several Indian missile systems.

"I don't know what evidence these people have, or what their motives are," Jiang said, referring to the researchers.

The spokesperson added that China could investigate if these allegations were provided with evidence.

"Our policy is very clear. We resolutely oppose all Internet crime, including hacking," she said.

The "cyberspies" used popular online services, including Twitter, Google Groups and Yahoo mail, to access infected computers, ultimately directing them to communicate with command and control servers in China, said the report released by the Munk Centre, entitled Shadows in the Cloud.

"We have no evidence in this report of the involvement of the People's Republic of China or any other government," wrote the authors.

They concluded the network was likely run by individuals with connections to the Chinese criminal underworld, and information "might have been passed to branches of the Chinese government".

Stolen documents recovered by the researchers contained sensitive information taken from India's National Security Council Secretariat, the group of researchers said.

"We have heard about the hacking report and the concerned department is looking into the case," said Sitanshu Kar, spokesman for the Indian Defense Ministry.