Up to 65,000 people in north-eastern Nigeria have fled their homes after an assault by armed groups on a border town on Wednesday, while attacks that appear to be targeted have forced a temporary halt to aid operations, U.N. agencies said.

Local officials and a resident said on Wednesday that at least eight people had been killed in the attack on Damasak by suspected Islamists, and that hundreds had fled across the border to Niger, a few kilometres away.

"Following the latest attack on Wednesday 14 April, the third in just seven days, up to 80 per cent of the town’s population - which includes the local community and internally displaced people -- were forced to flee," Babar Baloch of the U.N. refugee agency UNHCR, told a Geneva briefing.

Jens Laerke, spokesman for the U.N. Office for the Coordination of Humanitarian Affairs (OCHA) told the same briefing that aid operations had been temporarily suspended.

"The situation on the ground is extremely critical and if this continues it will be impossible, maybe for longer periods of time, for us to deliver aid to those who desperately need it," he said.

Laerke added that humanitarian workers appeared to be targets, amid reports of house-to-house searches for aid workers and the burning of their offices. UNHCR has relocated its staff from Damasak town due to the risks, Baloch said.