Security has been stepped up at MI5 following the theft, which has caused extreme embarrassment for the security agency and the government.
The UK's Police Special Branch has launched an investigation into the theft of the Ã,£2,000 computer, which took place on 4 March.
A spokeswoman from the Home Office said that while the UK government does not perceive the crime as a threat to national security because the data was encrypted, she admitted there is some "concern".
The representative confirmed to ZDNet that both the Home Secretary and the Prime Minister have been informed directly.
According to some press reports, the information on the laptop concerned Northern Ireland, although the Home Office would not confirm or deny this.
The spokeswoman said the computer's data was encrypted and confirmed that any information held on it would be very difficult to retrieve. She would not disclose what type of encryption was in place or how strong it is.
Richard Stagg, senior security architect with Information Risk Management said, "as long as the encryption is of an acceptable strength, then it's perfectly acceptable. The government has done everything that could be expected."
MI5 is responsible for gathering information on political and terrorist activity in Northern Ireland that could be highly relevant to the precarious Irish peace process.
According to reports, the laptop was stolen after being put on the floor at the station platform. The MI5 security officer gave chase to the thief, but lost sight of him in the busy station.
