As many as 30,000 people in Nigeria's commercial capital Lagos have been left homeless after their community was set ablaze and demolished this week, Amnesty International said.
It is not immediately clear how the fire began in the Otodo Gbame community, but residents told the human rights group that police officers blocked them from trying to put it out.
They said police returned later with a demolition team.
Lagos officials have warned that informal waterfront settlements pose a "security threat" and must be razed, a process which could affect hundreds of thousands of people.
However, Amnesty International said a Lagos court had granted an interim injunction against demolitions in communities including Otodo Gbame.
The group said those made homeless should be given alternative accommodation.
Lagos officials were not available for comment.