NIAMEY (Reuters) - Dozens of Boko Haram fighters have given themselves up to authorities in southern Niger, the interior minister said, days after the Islamist group suffered key losses over the border in Nigeria.

“Thirty-one young people from Diffa, who were enrolled a few years ago in Boko Haram, decided to surrender,” minister Mohamed Bazoum wrote on Twitter on Tuesday, above pictures of him touring the area near Nigeria’s northeast border.

The fighters arrived in the remote desert town of Diffa in groups and were being held by local authorities.

“I learned that the first who surrendered were not arrested, and I surrendered,” a former Boko Haram combatant told national television.

“We expect a pardon from the government so that we can participate in the development of the country and help us get rid of the trauma.”

In June, tens of thousands of people fled Diffa as Boko Haram swept the region. Five Niger soldiers were killed by the militants near Diffa in September.

In a statement carried later on national television, Bazoum said the government would welcome the former fighters “with open arms”, adding: “All those who have parents who are with Boko Haram can tell them to return. Boko Haram is now weak.”

Boko Haram has killed 15,000 people and displaced more than 2 million during a seven-year insurgency aimed at creating an Islamic state in Nigeria. In recent years its attacks have spilled into neighboring Niger, Cameroon and Chad.

Hundreds of Boko Haram fighters surrendered in Chad in October and November as the group ceded territory.

The group controlled an area about the size of Belgium in early 2015 but has since been pushed back by international forces including troops from Niger. Nigeria’s army captured its last enclave in the vast Sambisa forest on Friday, President Muhammadu Buhari said on Saturday.