Attackers burnt part of a mosque complex on Tuesday in the south Nigerian city of Benin, where clashes earlier killed five and displaced more than 10 000, a Red Cross official said.
"We have recorded so far five deaths -- on both sides, those that have been attacked and the attackers," said Dan Enowoghomwenwa, secretary general of the Nigerian Red Cross in Edo state, said.
"We have over 10 000 internally displaced persons in various places."
The attacks started on Monday amid street protests against soaring fuel prices, when a crowd separated from the main demonstration and attacked a mosque and terrorised residents of mainly Hausa neighbourhoods.
Hausas are the largest ethnic group in Nigeria's north and are overwhelmingly Muslim.
The Red Cross official could not specify who was behind the attacks, only saying there were "indigenes" targeting northerners.
Witnesses said an Islamic school adjacent to a mosque was burnt on Tuesday, as was a bus parked next to it.
"One of the old buildings at the mosque was burnt down but the new one was vandalised," said Enowoghomwenwa. "A 32-seater bus in the compound was burnt too."
Nigeria, Africa's most populous nation and largest oil producer, is roughly divided between a predominantly Christian south and mainly Muslim north.