Bring Back Our Girls (BBOG) campaigners take part in a protest procession marking the 500th day since the abduction of girls in Chibok, along a road in Abuja

A Bring Back Our Girls (BBOG) campaigner shouts slogans during a protest procession marking the 500th day since the abduction of girls in Chibok, along a road in Lagos

Bring Back Our Girls (BBOG) campaigners take part in a protest procession marking the 500th day since the abduction of girls in Chibok, along a road in Abuja

Bring Back Our Girls (BBOG) campaigners take part in a protest procession marking the 500th day since the abduction of girls in Chibok, along a road in Abuja