Families affected by Manchester Arena attack say MI5 must be more open to scrutiny

A memorial in the aftermath of the bombing in May 2017. Inquiry into the attack found it could have been stopped if MI5 had acted on crucial intelligence in the months leading up to it. Photograph: Christopher Thomond/The Guardian

Families affected by the Manchester Arena bombing have said MI5 failed them and must be more open to scrutiny.

In a letter sent to the prime minister seen by the BBC, the families demanded the Security Service be fully included in a new law designed to stop cover-ups in public life.