Former Guardian editor Alan Rusbridger warned this morning editors will “betray future generations of journalists” if they don’t “push back hard” against the so-called snooper’s charter.

The Investigatory Powers Bill outlines widespread powers for the state to access digital communications and currently includes little protection for journalists and their sources.

It was approved by the House of Commons this month and now goes to the House of Lords for further debate.

Rusbridger told the IBC legal conference in London: “It is the biggest threat to the press at the moment.”

He noted that the fact UK police secretly access telecoms data in order to identify journalists’ sources came out by “accident” in the Plebgate and Chris Huhne speeding points investigations .

He said: “There’s been some anger about this, but we haven’t seen anything like the level of journalistic anger about this as we have seen about the right to read about celebrities in paddling pools [a reference to the celebrity ‘threesome’ injunction involving The Sun].”

He added: “This is a fundamental threat to journalists and what we do…Even 18th century judges thought there was something troublesome about seizing the papers of a journalist…

“But the minute it moves from physical form into the digital form you get a shrug of the shoulders.

“We see this as probably inevitable.”

Of the widespread state spying powers currently “flying through Parliament” in the Investigatory Powers Bill, he said: “This is what Edward Snowden warned us about.”

“It seems to me an incredibly worrying thing.”

At present the Investigatory Powers Bill contains one extra protection for journalists, concerning police requests to view telecoms records (who called who and where) in order to identify their sources.

Under the current wording of the bill, such requests must be approved by a judicial commissioner who must consider the “overriding public interest”.

The requests would be made in secret to telecoms providers.

News publishers and the National Union of Journalists are campaigning for journalistic source protection to be woven throughout the bill.

Rusbridger cited the 2015 Interception watchdog report, prompted by the Press Gazette Save Our Sources campaign, which found that police had accessed the telecoms records of 82 journalists in a three-year period in order to secretly identify their confidential sources.

He said: “Yet we have writers saying it is difficult to see the harm in the state having access to all of our emails.

“If this becomes entrenched it will lead to sources dying, because people in other countries look to Britain and see Britain as a country which has high standards of freedom of speech, if we shrug that gives a terrible example to the rest of the world.”

He said state spying also threatened the ability of journalists to tell sources they can protect their anonymity any more.

The police source who told The Sun about former Cabinet Minister Andrew Mitchell’s foul-mouthed tirade against officers outside 10 Downing Street in 2013 was found and sacked as a result of Sun phone records being seized.

The Crown Prosecution Service refused to prosecute the Sun’s police source saying he acted in the public interest.

The Met Police seized the call records of three Sun journalists, as well as the newsdesk, and also used telecoms data to track their movements.

Rusbridger said: “When we talk to source and say ‘this is between you and me’, that’s a moral obligation. I’m not sure we can give that promise to sources any more.”

Talking about the Investigatory Powers Bill he said: “If we don’t put it on front pages and push back as hard as we can as this bill goes through Parliament we are going to betray generations of journalists, because journalism involving confidential sources is going to be very difficult indeed.”