IT systems at the Ministry of Defence have been hit by a computer virus.
The virus hit on 6 January and has been affecting the systems since then, leaving some staff without regular access to e-mail or the internet.
The MOD said claims that information from its systems had been sent to a Russian internet server as a result of the virus were "absolutely unfounded".
A spokesman said the virus was not aimed exclusively at the MoD, but was unable to say how the virus entered the system. The department says there is "no impact on current operations".
IT staff at the department have found a way to clean the infected systems and prevent re-infection. The system has been tested and is being implemented.
An MoD spokesman said, "The majority of systems are working normally however, remedial action is ongoing on some systems, so for those people who are still off-line normal business will resume as quickly as possible."