Downing Street are being forced to review their security have a hoax caller was put through to Prime Minister David Cameron.
David Cameron
The caller pretended to be Robert Hannigan, the head of spy agency GCHQ and was patched through to Mr Cameron - who hung up after a short call when he realised that it was a hoax. Downing Street was quick to confirm that no sensitive information was disclosed to the individual.
This was the second of two hoax calls as Mr Hannigan's mobile phone number was given out when this hoaxer called the organisation earlier in the day. However, this is not a phone that is used for calls that involve classified or sensitive information.
At the moment, no one has taken responsibility for the calls but steps are being taken to look in to the matter and tighten up security.
A government spokesperson said: "Following two hoax calls to Government departments today, a notice has gone out to all departments to be on the alert for such calls.
"In the first instance, a call was made to GCHQ which resulted in the disclosure of a mobile phone number for the director. The mobile number provided is never used for calls involving classified information.
"In the second instance, a hoax caller claiming to be the GCHQ director was connected to the Prime Minister. The Prime Minister ended the call when it became clear it was a hoax."
This is not the first time that Downing Street has been caught up by a hoax caller, after Tony Blair received a call from a man claiming to be William Hague.
Margaret Beckett was a victim of Rory Bremner in 2007, when the comedian phoned her pretending to be the then Prime Minister Gordon Brown. During their phone conversation, Beckett discussed a possible cabinet reshuffle with Bremner.
The Queen was also conned back in 1995, when she spent nearly twenty minutes on the phone with a man that she believed was the Canadian prime minister.