NEW DELHI: The Nuclear Power Corporation of India Ltd (NPCIL) on Wednesday accepted cyber attack on its system after issuing a denial on it a day ago."Identification of malware in NPCIL system is correct. The matter was conveyed by CERT-In when it was noticed by them on September 4, 2019," a statement issued by NPCIL on Wednesday said."The matter was immediately investigated by DAE ( Department of Atomic Energy ) specialists. The investigation revealed that the infected PC belonged to a user who was connected in the internet connected network for administrative purposes. This is isolated from the critical internal network," it said adding the networks are being monitored continuosly.The statement said that the plant systems were not affected by the malware.On Tuesday, the company had denied cyber attack on its Kudankulam Nuclear Power Plant, one of the county's most advanced such station in India. NPCIL had on Tuesday said any cyber attack on the Nuclear Power Plant Control System is not possible its network is "stand alone" and not connected to internet.Congress MP Shashi Tharoor had on Tuesday asked for an explanation from the government. "This seems very serious. If a hostile power is able to conduct a cyber attack on our nuclear facilities, the implications for India's national security are unimaginable. The government owes us an explanation," he had tweeted.