Authorities in Niger have started expelling 4,000 Arab settlers into neighbouring Chad, but community leaders have warned the government’s decision could kick-start inter-ethnic violence in the dirt-poor country.

Niger's authorities announced plans to repatriate Mahamid Arabs from the region around the town Diffa, close to the border with Chad, in the vast country’s remote southeast region on Tuesday.

The expulsions will be conducted "with respect for human dignity" and only target people “not in conformity with Niger's laws,” Niger's interior Minister Mounkaila Modi pledged on national television.

On Wednesday, Arab leaders said the Nigerien armed forces were patrolling the sandy streets and roads in Diffa and the surrounding region, harrying the Arab population to pack their bags. Trucks full of women, children and old people had been already sent to the town of Kabelawa, 100 km to the north of Diffa on the Chadian border, they added.

A government official in the Diffa region confirmed to IRIN that the repatriation operations actually started on Friday, before the government’s official announcement.

“Regrouping operations started on Friday. We must gather the people and livestock in Kabelawa, but it will take a terribly long time for them all to return to Chad", said Abdourahmane Ari, a government official at Nguigmi, around 100 km northeast of Diffa.

Some of the 4,000-strong Mahamid community has been in Niger since a devastating drought in 1973 caused upheavals throughout the region and forced them to flee their homes near Biltine in eastern Chad, more than 1,000 km east.

More of the Arab tribe followed in the 1980s, when a brutal civil war made Chad one of the most dangerous places to live in the world.

A census carried out in Niger in 2001 showed many members of the Arab community had been issued national identity cards by local authorities.

But the Niger government said their presence has now become untenable because of quarrels with local inhabitants. It also said the Arabs pose a threat to national security, although did not specify how.

The Arab community in Niger said in a statement on Wednesday that “this decision made by the government is extremely dangerous... it will fuel the hatred between ethnic communities in Diffa and will lead inevitably to a widespread conflict whose wounds will take time to heal.”

The UN High Commissioner for Refugees (UNHCR) told IRIN it would send someone to Niger soon to see what - if anything - it could do.

"This group does not have refugee status, it is the very first time we hear about it", Helene Caux, UNHCR spokesperson in Geneva said. "We first need to evaluate if these people will suffer discrimination if they go back to Chad."

Jean-Baptiste Mattei, spokesperson for the French government, said France “is paying close attention to this question for the sake of avoiding the risk of regional destabilisation. We are in touch with the Nigerien authorities and the UN to get the most detailed analysis of the situation, particularly on the humanitarian angle”.

The report accompanying the 2001 national census, obtained by IRIN, hinted at mounting tension between the Mahamids and dominant ethnic groups in the northeast of Niger, the Touaregs and Toubous.

"Mahamid, nomad pastoralists coming from Chad, are very restive,” the report said. “Cohabitation with the other communities is strained,” it added.

According to the report, the reduction of pastoral land because of successive droughts, combined with the growth of large camel herds, had fuelled discord between pastoralists and herdsmen in the region.

“They do not stand by the common pastoral rules. Conflicts erupt very often around the wells that they consider as state owned. They use them as they want", an indigenous local chief was quoted as having said.

"Some inhabitants think the Mahamid must leave the region, unconditionally and without delay. A relative unanimity prevails among the population who want them to leave the area", the 2001 report concluded.

Niger’s president, Mamadou Tandja, originally comes from the Diffa region, which has a similar ethnic make-up to Chad. The region was at the centre of an unsuccessful military uprising in 2002.