In a letter to The Guardian, senior lawyers condemned the bill, which sets out a legal framework facilitating GCHQ’s mass interception of data, as fundamentally flawed.

Law lecturer Dr Cian Murphy, who co-ordinated the letter and its signatures, told Irish Legal News: “The Bill at present is entirely unfit for purpose. The case for bulk surveillance, and for the use of Internet connection records, has not been made.

“Judicial Commissioners need to be able to do a full review of interception requests - or the ‘double-lock’ might simply be left on the latch.”

The letter is signed by chair of the Bar Human Rights Committee,Kirsty Brimelow QC, Professor Sir Geoffrey Bindman QC, former Court of Appeal judge Sir Stephen Sedley, Michael Mansfield QC and Philippe Sands QC.

Solicitor Darragh Mackin of Belfast law firm KRW Law, one of the signatories to the letter, told Irish Legal News: “It is expressly clear that the draft bill does not meet the standards that are required by international law on the right to privacy.

“It is therefore inescapable that the law must be revised to make it fit for purpose.”

The government has argued bulk interception of private data is necessary as a first step in pursuing terrorists and criminals and that extraneous material is never read.

However, the United Nations special rapporteur on privacy, Joseph Cannataci, said last week that the bill would legitimise mass surveillance.

The letter states: “First, a law that gives public authorities generalised access to electronic communications contents compromises the essence of the fundamental right to privacy and may be illegal. The investigatory powers bill does this with its ‘bulk interception warrants’ and ‘bulk equipment interference warrants’.”

It goes on to argue the bill is too broad “because it allows ‘targeted interception warrants’ to apply to groups or persons, organisations, or premises.”

Finally, there is no provision in the bill for reasonable suspicion or a requirement to demonstrate criminal activity or a threat to national security.

The letter adds: “These are international standards found in judgments of the European court of justice and the European court of human rights, and in the recent opinion of the UN special rapporteur for the right to privacy. At present the bill fails to meet these standards – the law is unfit for purpose.

“If the law is not fit for purpose, unnecessary and expensive litigation will follow, and further reform will be required. We urge members of the Commons and the Lords to ensure that the future investigatory powers legislation meets these international standards. Such a law could lead the world.”

Eric King, director of Don’t Spy On Us, said: “The government’s approach to this important reform has been wrong from the very beginning: they’ve sought to make bad habits lawful, rather that chart a new and legitimate course for the future.

“The fact so many of the bill’s key provisions fall short of international standards cannot simply be pushed aside. A full redraft of this flawed bill is needed for it to stand the test of time. Anything less is simply a waste of parliament’s time.”

The SNP and Liberal Democrats will oppose the bill in today’s vote while Labour will abstain.