A man purporting to be the prank caller who was put through to David Cameron's phone after posing as the director of GCHQ has claimed he was high on drink and drugs at the time.
"I've just made complete monkeys out of GCHQ. I've got the mobile number of the director," the unidentified prankster told the Sun (£).
"What's more, I am off my face on booze and cocaine... I'm definitely going to do it again. It was so easy."
It is not known if the same man was behind both the calls, but according to a government spokesperson a call was made to GCHQ on Sunday and the director's number, Robert Hannigan, was given out. Subsequently a man claiming to be Hannigan was put through to David Cameron's mobile phone.
"The prime minister ended the call when it became clear it was a hoax. In neither instance was sensitive information disclosed," the spokesperson said.
"Both GCHQ and Number 10 take security seriously and both are currently reviewing procedures following these hoax calls to ensure that the government learns any lessons from this incident."
The mobile number given out for Hannigan was for an unclassified phone rather than one of the secure lines used for sensitive communications.
This is not the first successful prank call to Number 10. In 1998 radio DJ Steve Penk was put through to Tony Blair after calling Downing Street pretending to be Tony Blair.
Additional reporting by PA