Police should be given a cyber ‘key’ to unlock encrypted messages in ‘exception circumstances’ such as child abuse and terrorism, one of Britain’s most senior police officers has said.

Chief Constable Simon Bailey told the Independent Inquiry into Child Sexual Abuse (IISCA) yesterday he wanted tech giants to build a back door into apps, which he said were making it “so much harder” to catch paedophiles.

Mr Bailey, the National Police Chiefs' Council (NPCC) lead on child protection, said he felt the public would not oppose such a feature if they knew it was aimed at people sharing indecent images.

Messaging apps such as Facebook’s WhatsApp and Apple’s iMessage have end-to-end encryption meaning that even the companies cannot see the contents.

Mr Bailey said: “There needs to be with these (tech) companies some form of key that would afford access and it’s a very clear understanding for all customers that that key to break the privacy would only be used in exceptional circumstances.

“The list would be countering terrorism, dealing with indecent imagery and sexual abuse of a child.”

Giving evidence to IISCA last week, Melissa Polinsky, a senior security executive for Apple, said the company saw encryption as “a fundamental right for customers” to protect their sensitive data such as bank details and personal photos.