The attack last evening in Ngala, near the border with Cameroon, came as two people were killed in an explosion outside another camp in the Borno state capital, Maiduguri.
In Ngala, a civilian militia member, Umar Kachalla, said jihadists in two pick-up trucks fired a rocket-propelled grenade at the camp, which houses some 80,000 people.
"They (Boko Haram) fired an RPG into the camp from behind the fire fence, killing seven people and injuring several others," he told AFP from the neighbouring town of Gamboru.
Ngala resident Abubakar Yusuf, who corroborated Kachalla's account, said: "The casualties were relatively minimal because most people had retired for the night."
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The camp in Ngala was set up in January last year after the return of thousands of Nigerian refugees from Cameroon, where they had fled the fighting.
Boko Haram seized the trading hubs of Gamboru and Ngala in August 2014, during the group's rapid seizure of territory across Borno state and the wider northeast.
But despite the recapture of the area, Boko Haram fighters still launch sporadic attacks, laying ambush to troops and vehicles as well as attacking and abducting farmers.
Nigeria's military and government maintains the Islamic State group affiliate is a spent force but continued attacks underlines the lingering threat, particularly to civilians.
Eight farmers were killed in a series of raids on farming communities on Wednesday and Thursday. Four others were shot dead on Tuesday.
Many of the victims had returned home to try to grow crops to alleviate acute food shortages that have left hundreds of thousands of people on the brink of starvation.
In Maiduguri yesterday, two people were killed in an explosion outside the Muna Garage camp for internally displaced people (IDPs).
Babakura Kolo, from the civilian militia assisting the military with security, said two women were asked to get out of a taxi laden with bags of charcoal at a checkpoint.
"One of the women tried to run into a crowd nearby but the explosives concealed under her hijab went off prematurely," he said.
Five people -- the taxi driver, another passenger and three men in the rickshaw -- were injured, they added.
Kolo, who was at the scene, said a second female suicide bomber was also killed with the first in the initial blast.