David Davis, the former shadow home secretary, criticised Mrs May after she said criminals, terrorists and paedophiles would oppose the new law allowing the police and security services to monitor every email and internet visit, adding: “It’s a question of whose side you’re on.”
Nick Clegg, the deputy prime minister, is thought to be angered by Mrs May’s claim that blocking the new law “could see people dying” as he considers whether to withdraw Liberal Democrat support for the draft Communications Data Bill, which many in the party say is too great an intrusion on civil liberties.
A Liberal Democrat source said: “These comments are ahead of themselves.
“We haven’t even heard the verdict of the committee which was set up to look at this highly complex and controversial area of policy. The case for this legislation still has to be proven.”
Mr Davis said: “There are perfectly legitimate arguments to be had. But what you can’t do is effectively impugn the motives of people who disagree with you.
“That’s what she did, and frankly I wasn’t going to tolerate it.”
He raised a point of order in the Commons asking if the home secretary was going to explain herself and accusing her of “traducing a large number of people in this House” while undermining the work of parliamentary committees examining the Bill.
Mrs May should wait for the MPs and peers, who have heard from legal and technical experts, to report in the next few days and then offer a proper debate, “not try to assault the reputation of those who disagree with you”, Mr Davis said.
“This is a very serious issue, nobody disputes the seriousness of it.”
Ministers say the Bill ensuring communications companies keep details of every phone call, email and website visit of their customers for up to a year is necessary to allow the police and intelligence agencies to stay ahead of terrorists and major criminals who are able to exploit all forms of modern communications.
The authorities will be able to see who is in contact with whom and when, but not the content of any communication.
A joint committee of MPs and peers has been examining the proposals and their report is expected to conclude that the Home Office has failed to make a case.
It will also say that the move invades privacy and could leave the stored data open to abuse.
But Mrs May said the measures would help prevent another July 7-style attack on Britain’s streets and insisted “we could see people dying” if the new law was blocked.
“The people who say they’re against this bill need to look victims of serious crime, terrorism and child sex offences in the eye and tell them why they’re not prepared to give the police the powers they need to protect the public,” she told The Sun.
“Anybody who is against this bill is putting politics before people’s lives.”
Mrs May also denied the Bill amounted to “snooping”, saying the government would not be looking at everybody’s emails or at every webpage everybody has looked at.
Rachel Robinson, of the civil rights group Liberty, said: “It’s disappointing to see senior politicians stoking fear rather than informing debate.”