Simon Bailey will use his final day as Norfolk's chief constable to criticise social media companies for "putting profit over safeguarding children".

Mr Bailey, who has led the police force in the county for the last eight years, announced his intention to retire in March.

Wednesday, June 30, marks his last day after a 35-year career with Norfolk Constabulary.

He will use it to speak at Anglia Ruskin University's Policing Institute for the Eastern Region (PIER21) conference, at which he will warn Facebook's decision to introduce blanket end-to-end encryption threatens to "turn the lights off" on the issue of online child sexual abuse, allowing offenders to upload, share and view indecent images undetected.

Mr Bailey will say: "Unfortunately, the technology industry continues to put profit before safeguarding children.

"Facebook is already the most used platform for the sharing of indecent images and yet they are planning to wilfully blind themselves by introducing end-to-end encryption across their services. This will simply turn the lights off on our ability to effectively monitor this activity. It is open to Facebook to change those plans.

"Social media companies have the ability to make the uploading, viewing and sharing of indecent images so much harder, but they choose not to invest in the technology to eradicate it. In fact by applying end-to-end encryption irresponsibly they are making it easier.

"The technology is there to stop people uploading these images, but they continue to put profit over safeguarding children."

He will also reflect on his time as the National Police Chiefs Council's national lead on child protection, and call on social media giants to help in the fight against online child sexual abuse.

Mr Bailey will say: "During the last seven years the UK has become far better at targeting offenders and investigating all forms of sexual abuse, we are world leading targeting online abuse, but despite this response, the number of victims and offenders is increasing.

"The police and the NCA are doing everything we can but the onus now needs to be on the social media giants, who are still absolving themselves of responsibility."

Paul Sanford will replace Mr Bailey as the new temporary chief constable for Norfolk from Thursday, July 1.