A number of prominent international activists and celebrities have written to the Nigerian President, Muhammadu Buhari, demanding justice for protesters jailed for demonstrating against police brutality.

The letter, signed by household names such as the campaigner Greta Thunberg and the singer Alicia Keys, asks the Nigerian leader to free the protesters, investigate the armed forces and ensure the right to peaceful protest.

They say that as supporters of the Black Lives Matter movement they can’t stay silent when atrocities are committed by African countries.

In October, demonstrations against police brutality in Nigeria descended into violence when soldiers opened fire on protesters in the commercial hub of Lagos. Since then activists involved in the demonstrations say they’ve been targeted by the authorities. A number of them have had their bank accounts frozen by the Nigerian Central Bank and some have been detained without charge, before being eventually released.