The United Nations has expressed concern over the safety of thousands of refugees and internally displaced persons following the deadly attack on Toumour in southeastern Niger's Diffa region, near the border with Nigeria.

The 12 December attack that has since been claimed by Boko Haram left at least 28 people dead and hundreds wounded.

According to the UN refugee agency (UNHCR), Toumour shelters more than 30,000 refugees and internally displaced persons.

"Following the attack, most of the population fled to the bush, with some people returning only at daytime," said Babar Baloch, UNHCR spokesperson.

Babar also noted that attackers destroyed nearly two-thirds of the town's homes, burned the Toumour market to the ground, and killed more than a thousand cattle, according to local reports.

On his part UN Secretary-General Antonio Guterres condemned the attack and reiterated the UN's commitment to supporting national efforts to consolidate democratic governance, promote social cohesion and boost sustainable development.

The Lake Chad basin has seen an increase in extremist violence over the past few months that has forced hundreds of thousands into the Diffa region.

Baloch said the UNHCR and its partners are providing protection and humanitarian aid to more than 265,000 people in the region.