The police and security services will not be able to spy on MSPs or MPs without the Prime Minister's approval it emerged as ministers confirmed plans for new snooping laws.

Under the proposals, internet firms will have to store data on people's web use for up to a year.

Communications companies will also be legally required to help spies hack in to suspects' phones and computers.

The Consecrative Government suggested that the proposals represented a climbdown on previous plans following an uproar over civil liberties.

Ministers also pledged to write the so-called 'Wilson doctrine', that MPs' communications should not be intercepted by the intelligence services, into law for the first time.

Home Secretary Theresa May said that the new laws would provide additional safeguards to protect the sensitive communications of politicians including MPs, peers, MSPs and MEPs.

But critics, including Tory backbenchers, warned that the changes did not go far enough.

Joanna Cherry, the SNP’s Home Affairs spokesman, said that only “time and careful scrutiny” would determine whether the Bill fulfils its aims.

She said: “The Home Secretary sought to reassure us today that this Bill will not be a snooper’s charter and whilst I am prepared to accept that the Government may have rolled back to some degree from their previous plans – it will take careful consideration of the draft Bill to be sure that this is the case.

"We can all agree that we have a responsibility to protect the rights of our fellow citizens whilst also being realistic about the threats we face. Access to communication which would otherwise be private must always be shown to be necessary, targeted and proportionate.

"We are concerned that the Government’s proposed hybrid scheme of a mixture of political and judicial scrutiny - doesn’t go far enough and would simply add an extra layer of bureaucracy.’’

Under the plans communications firms would have to hold data for 12 months.

They will also be legally required to help spies hack into suspects’ phones and computers, if they have a warrant.

Home Secretary Theresa May described the publication of the new draft Investigatory Powers Bill as "a decisive moment".

The powers should ensure there s no area of cyberspace that could be a “haven for those who seek to harm us, to plot, poison minds and peddle hatred under the radar".

But she also pledged “world-leading oversight" of the new regime.

Around seven High Court judges will be appointed and given unprecedented powers to veto warrants.

However, in urgent circumstances, including where there is a threat to life, Mrs May would be able to issue a warrant without a judge.

Officials described the date that will have to be kept, Internet connection records (ICRs), as the equivalent of a phone bill.

Sites to which a customer connects will be detailed, but not their full browsing history.

Councils will be banned from accessing ICRs, while a new offence of "knowingly or recklessly obtaining communications data" will be created for cases of abuse.