Ms Rudd criticised Facebook’s WhatsApp after it emerged that Khalid Masood used the messaging service moments before ploughing into pedestrians on Westminster Bridge.
Acting Metropolitan Police Chief Commissioner Craig Mackey said on Wednesday that officers faced “challenges” investigating terror attacks because messages on several platforms were encrypted, making it difficult for police to read them.
WhatsApp messages are protected by end-to-end encryption which converts them into indecipherable sequences until they reach the recipient’s device. The system is commonly used by communications services to protect users’ privacy.
Firms will be asked at Thursday’s meeting what they are doing to combat terrorists’ use of their products.
Microsoft president Brad Smith said this week: “Our team responded in under 30 minutes last week to verify that the legal order was valid and provided law enforcement the information that was sought.
“Our global team is on call 24/7 and responds when it receives a proper and lawful order. This of course is different from helping a government outside the rule of law to turn over private information or hack or attack a customer, which we’ve said clearly we will not do.
“We’re committed both to protecting public safety and safeguarding personal privacy, and we believe that proper legal process is the key to striking this balance.”
Microsoft confirmed that it had received lawful orders seeking email information relating to the London terror attack, and said it had “promptly provided the information requested”, as it had done following the attacks in Paris and Nice.
On Sunday, Ms Rudd told the BBC’s Andrew Marr Show it was “completely unacceptable” that Mr Masood’s WhatsApp messages were…