Media playback is unsupported on your device Media caption Speaking on LBC, Nick Clegg described a "new low point in coalition relations"

Nick Clegg has attacked the home secretary for "outrageous" claims that his party put children at risk by blocking new data monitoring powers.

The Lib Dem leader told LBC radio that he had demanded an apology from Theresa May, and that her conference speech was a "low point in coalition relations".

Mrs May had said that cases involving threats to children's lives and others were dropped because of missing data.

But David Cameron backed her, saying her speech had been "right".

The Conservatives and the Liberal Democrats went into government together after the 2010 general election, but both parties have been taking steps to differentiate themselves ahead of the election next May.

The deputy prime minister was responding to Mrs May's speech to the Conservative Party conference this week, in which she attacked her coalition colleagues for their stance on the Communications Data Bill.

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Mrs May accused the Lib Dems of having "torpedoed" the bill - and said over six months, the National Crime Agency had dropped at least 20 cases as a result of missing communications data, 13 of which had involved a threat to the life of a child.

But Mr Clegg told his regular phone-in show on LBC the facts were "quite different".

The cases had been dropped because IP addresses were not being properly matched to individual mobile devices, he said, accusing the Home Office of "dragging their feet to do something about it".

'Forgetful'

He said that the suggestion that his party's opposition to what he calls a "snooper's charter" had put children's lives at risk was "absolutely appalling".

"I try and be very discreet about all the yah-boo and all the rest of it about the disagreements that might happen in government.

Analysis The Communications Data Bill, or "snooper's charter" is an issue the Conservatives and Lib Dems have clashed on before. The significance this time, is the timing. Nick Clegg says the home secretary's speech was a "new low point in coalition relations." That's quite a claim given the ups and downs of the coalition partners over the last four and a half years, not least of all splits over education and House of Lords reform. Just seven months from the general election the coalition partners are drawing their battle lines. Expect to see far more of this sort of language from both parties as they seek to distance themselves from each other and appeal to their traditional voters. It will continue, no doubt, with next week's Liberal Democrat conference in Glasgow.

"I think to say about another politician, particularly someone that you are governing with: 'You are putting children at risk', when it is not true, is a level of outrageous information that I have not witnessed in the four and half years that I have been in this government."

Mr Clegg said he had written to Mrs May, asking for an apology.

But Mr Cameron said: "I thought Theresa made a very strong speech about how important it is that we protect people from the dangers of terrorism on our streets.

"She set out a series of measures we have taken and some measures that a Conservative-only government would take to make us even more safe and I think that was the right thing to say."

A source close to Mrs May said: "Maybe Clegg is becoming as forgetful as Ed Miliband but we haven't received a letter from him.

"It's interesting to see how the Lib Dems react to the logic of their position being aired in public but the truth is, that they are putting lives at risk right now.

"If they want to do something about that, they can start talking to us about returning to the Communications Data Bill that Nick Clegg first torpedoed on his radio show two years ago."

Plans for a Communications Data Bill were mentioned in the coalition's Queen's Speech in 2012.

But in April 2013 Mr Clegg said he would veto them, telling party members plans to keep records of every website visited and activity on social media did not fit with a coalition pledge to move away from Labour's "database state".

The bill would have extended the range of information telecommunications firms had to store for up to 12 months, including the time, duration, location and recipients of messages sent on social media, emails and phone calls - although a warrant would be needed to view the content of messages.

Lib Dem MP Duncan Hames has written to the most senior official at the Home Office demanding a probe into a Daily Mail story in which a "Home Office source" was quoted swearing about Mr Clegg.

He said this had been an "inappropriate and personal attack" and a "clear breach" of the Civil Service Code and Special Adviser's Code of Conduct.