At least six people have been killed in attacks by suspected jihadists in Niger near its border with Burkina Faso, authorities said on Friday.

"The provisional toll is... six dead including a policeman, two customs officers and three civilians" during the attacks overnight from Wednesday to Thursday, the interior ministry said in a statement. 

Ten others were wounded when heavily armed gunmen simultaneously attacked a border post and a bridge near the border town of Makaldoni, it said.

Local sources had told AFP earlier that the attack had caused deaths and casualties, but exact numbers were not known.

The Makaldoni border post -- where customs officers, gendarmes and police officers are stationed -- lies in a zone frequently targeted by jihadists.

Makalondi is the last major town in Niger before the Burkina Faso border, some 100 kilometres (65 miles) southwest of the capital Niamey. 

It lies in the Tillaberi region, which is in the so-called tri-border area -- a flashpoint zone where the frontiers of Niger, Burkina Faso and Mali converge.

Niger, the world's poorest country according to the UN's Human Development Index, has to contend with two jihadist insurgencies.

As well as the attacks in the west from groups such as the Islamic State in the Greater Sahara (ISGS), it also has to deal with Boko Haram and the Islamic State West Africa Province (ISWAP) in the southeast, near the border with Nigeria.

On Wednesday, the regional authorities in Tillaberi announced that a number of petrol stations would be closed in several counties in a bid to disrupt fuel supplies for the jihadists, who typically move around by motorcycle or 4x4 vehicles.

The authorities had already closed markets and refugee camps and declared a ban on movement by motorbike in sensitive areas.