"Attempts have always been there to hack our computers, but we have our security systems in place," a PMO official told IANS.
"There has been no breach on our security system, we are absolutely safe," PMO media adviser Harish Khare told IANS.
According to a Headlines Today TV channel report, hackers from China had targeted computers in the PMO around Dec 15 last year and "investigators are still coming to terms with the depth of the damage".
It said the hackers had aimed at the "cream of India's national security set-up: National Security Advisor M.K. Narayanan, Cabinet Secretary KM Chandrashekhar, PM's Special Envoy Shyam Saran and Deputy National Security Advisor Shekhar Dutt. The four and up to 26 others were squarely in the crosshairs of the hacking attempt".
"The hacking spyware itself was embedded in a PDF document. And the Trojan Horse was programmed to carry out an array of functions, including downloading files, accessing emails and passwords and also accessing the desktop from a remote location," it said.