British home secretary Amber Rudd has said end-to-end encryption in messaging apps is "absolutely unacceptable" in the wake of the Westminster terror attack.

Rudd made the push for increased surveillance powers after reports that terrorist Khalid Masood used the messaging app WhatsApp two minutes before launching his attack.

Encrypted platforms like WhatsApp allow users to send private messages which are heavily encoded, using end-to-end encryption. This means messages and voice calls are encrypted on the sender's device and then decrypted on the receivers' device. This prevents governments and hackers eavesdropping on communications.

Rudd made her claim, despite it not being known whether Masood sent any messages while using WhatsApp, whether he was in contact with anyone, nor without information about who he may have been in contact with.

Despite the lack of evidence about what role WhatsApp played in the attack on Westminster, Rudd has said tech companies should not make encryption made available to its users, despite WhatsApp having more than 1bn users worldwide.

Appearing on BBC's The Andrew Marr Show on Sunday (26 March), Rudd said: "[Encryption] is completely unacceptable. There should be no place for terrorists to hide.

"We need to make sure that organisations like WhatsApp – and there are plenty of others like that – don't provide a secret place for terrorists to communicate with each other.

"It used to be that people would steam open envelopes or just listen-in on phones when they wanted to find out what people were doing – legally, through warrantry [sic] – but in this situation, we need to make sure that our intelligence services have the ability to get into situations like encrypted WhatsApp."

However, had security services had access to Masood's messages, it is not clear they would have been able to prevent such an attack. London's Metropolitan Police Service confirmed that the entirety of the Westminster attack lasted a total of 82 seconds.

It is common for security services to call for increased snooping powers following terrorist attacks, but it is often unclear how much impact it would make.

Britain's GCHQ has already amassed expansive spying capabilities, as disclosed by whistleblower Edward Snowden, and there are repeated instances of government misusing spying powers to snoop on ordinary UK citizens such as campaigners, journalists and lawyers.

The United Nations has twice expressed its concerns about Britain's spying programs, stating it deeply conflicts with the human right to privacy.

However, Rudd said she will be "calling in" companies like WhatsApp this week in an attempt to put an end to their encryption capabilities.

A spokesperson for WhatsApp told IBTimes UK: "We are horrified at the attack carried out in London earlier this week and are cooperating with law enforcement as they continue their investigations."