AMBER Rudd has been accused by Labour of “political grandstanding” after the Home Secretary called for the police and intelligence agencies to be given full access to messages on WhatsApp and other encrypted social media services.

It has emerged Khalid Masood, who killed four people and injured several others in last week’s terror attack on Westminster, had sent an encrypted message on WhatsApp just minutes before he embarked on his deadly rampage.

So-called end-to-end encryption means the authorities would not have been able to monitor the discussion Masood had.

At the weekend, Ms Rudd - who, in Whitehall on Thursday, will meet social media companies like WhatsApp owner Facebook - called on messaging apps that used encryption to install a so-called "back door" so the police and intelligence services could, with a court warrant, monitor the otherwise secure communications of those linked to terrorism.

During her visit to Scotland, Theresa May made clear she wanted to see “cross-fertilisation across police forces” in the fight against terrorism.

Meeting officers during a visit to a police station in Glasgow, the Prime Minister said dealing with terrorism meant there had to be a “multi-faceted approach,” involving forces across the whole of the UK.

Her spokesman, asked if the UK Government was now looking at banning end-to-end encryption, said what the Home Secretary had argued was that if there were “circumstances where law enforcement agencies need to be able to access the contents, they should be able to do so”.

He added: “Let's wait for the talks later in the week but the broad Government position would be these are companies which have fabulous technical expertise, they are world leading, and where they can do more to assist we would like them to do so.”

However, the plans have been criticised over their potential threat to mobile device security in general with the tech industry calling the use of encryption a vital tool in ensuring cyber security for everyday consumers; the technology is used to hide personal data, including financial information, from hackers and cyber criminals.

Sam Dumitriu, from the Adam Smith Institute think-tank, said Ms Rudd's call for access to encrypted services was "deeply misguided," stressing: "It is mathematically impossible to build a back door for just the good guys.

"It means building a back door to your private messages for Putin's favourite hacker Guccifer. It means opening up your private photos to perverts like the iCloud hacker. End-to-end encryption keeps us safe.”

He added: “Khalid Masood wasn't even on MI5's 3,000 strong list of suspected jihadis. Ending end-to-end encryption would not have stopped the Westminster attack but it would mean a free-for-all for cyber criminals and Putin's hackers.”

At Westminster, Diane Abbott for Labour made clear her party would oppose allowing open access trawl by the authorities for all messaging.

"Good counter-terrorism measures are nearly always intelligence led. In the cases of suspects or perpetrators of serious crime or terrorism, it is crucial that there is effective judicial oversight of the security services’ access to encrypted messages.”

The Shadow Home Secretary added: “Amber Rudd will be keen to set out exactly how the Government will ensure that law-abiding citizens’ privacy is not breached. Fighting terrorism is a serious business and should not be used for political grandstanding.”