No 10 said the caller claimed to be Robert Hannigan, director of government eavesdropping agency GCHQ. The Prime Minister ended the call when it became clear it was a hoax and no sensitive information was disclosed, Downing Street said. Security procedures are being reviewed at both No 10 and GCHQ, where a mobile phone number for director Mr Hannigan was disclosed to the caller. A government spokeswoman said: “The Prime Minister ended the call when it became clear it was a hoax. In neither instance was sensitive information disclosed. “Both GCHQ and No 10 take security seriously and both are currently reviewing procedures following these hoax calls to ensure that the government learns lessons from this incident.” The call to the Prime Minister was made to an official mobile but the conversation was understood to have been “quite brief” before the hoax was discovered. FOLLOW US Twitter | Facebook | Google+ ----------------------------------------- Subscribe to our DAILY NEWSLETTER (requires registration) ----------------------------------------- SCOTSMAN TABLET AND MOBILE APPS iPhone | iPad | Android | Kindle Meanwhile, the Conservative Party chairman has indicated the Prime Minister would take part in proposed live televised debates planned for the general election, despite continuing uncertainty over whether they will take place. Grant Shapps said final negotiations needed to take place with television companies, but added: “We are edging towards a solution on this, which is good.” In an earlier joint statement, the four major broadcasters confirmed plans for a 7-7-2 format – under which two debates hosted by the BBC and ITV would feature the leaders of the Conservatives, Labour, Lib Dems, Ukip, Greens, SNP and Plaid Cymru – while a third on Channel 4 and Sky would pit David Cameron against Ed Miliband in a clash of the two men most likely to emerge as prime minister. But the plans were condemned by Ukip leader Nigel Farage who claimed the debates now looked “less likely”. The Democratic Unionist Party also claimed that the proposal cannot be “legally defended” and the Lib Dems said they would continue to push for Nick Clegg to appear in all three events. The broadcasters said that if any of the leaders decide not to participate, “the debates would take place with those who accepted the invitation”. Proposed dates for the debates are 2, 16 and 30 April – with the final clash coming exactly a week ahead of the 7 May polling date. Asked if Mr Cameron would now take part in the debates, Mr Shapps said: “Yes, I think that’s right. The final negotiation needs to take place with the TV companies. I think they are, as David Cameron said, a good innovation.”