Belarus’s deputy interior minister has pledged to release all protesters by Friday morning, as evidence about beatings and mistreatment by police inside detention centres grew.

On Thursday night Alexander Barsukov told reporters outside the Okrestina detention centre in the capital, Minsk: “We will release everyone by 6am.”

Photographs from outside the detention centre showed detainees emerging to waiting friends and relatives late on Thursday night and early on Friday morning, but it was unclear if all detainees had been freed by the deadline set by Baruskov.