GENEVA: Hundreds of refugees who fled deadly Boko Haram attacks earlier this month are being sent back from Niger to northeastern Nigeria, the UN said Friday, voicing concern the repatriation might not be voluntary.

The UN refugee agency said it remained unclear whether the refugees were being forced to return home despite dangerous conditions.

“UNHCR is very concerned about the return to Nigeria from Niger on Jan. 14 of hundreds of refugees in a joint operation conducted by the governor of Borno State and the authorities in Niger,” UNHCR spokesman William Spindler told reporters in Geneva.

A Jan. 3 attack on the town of Baga in Borno state is thought to be the worst attack in Boko Haram’s six-year insurgency and feared to have killed hundreds, if not more.

Amnesty International and Human Rights Watch published separate satellite images Thursday that appeared to show massive destruction in both Baga and the adjacent town of Doron Baga.

HRW said 11 percent of Baga and 57 percent of Doron Baga were flattened, most probably by fire.

UNHCR said according to the information it had received, the refugees were transported in nine buses to Maiduguri, the capital of Borno state and the birthplace of the Boko Haram movement.

It said another 11 buses were ready in Niger’s border region of Diffa, where waves of Nigerians have fled recently in the wake of the upsurge in Boko Haram violence, to transport them back.