Ambush on troops took place on Tuesday near Tongo Tongo, close to the Niger-Mali border in the restive Sahel region.

The death toll from Tuesday’s ambush on Nigerien troops near the border with Mali has risen to 28, an army spokesman and security sources have said, as ISIL claimed responsibility for the attack.

The bodies of 11 soldiers who had previously been reported missing were discovered on Wednesday, security sources told AFP news agency.

“We have confirmation that the dead bodies of the eleven missing soldiers have been found, bringing the death toll to 28,” a source told AFP on Wednesday.

An army spokesman on Thursday confirmed the toll has risen to 28, Reuters news agency reported.

Later on Thursday, Islamic State of Iraq and the Levant (ISIL, also known as ISIS) claimed responsibility for the attack vie its propaganda media outlet, without providing evidence.

The attack on the military patrol took place near the town of Tongo Tongo, in the western Tillaberi region of Niger.

According to the local news website Actuniger, a patrol of 52 Nigerien soldiers came across a group of heavily armed men at Baley Beri, which resulted in a two-hour long fight.

It said that 22 soldiers returned to their base at Ouallam in three vehicles, citing local and security sources.

The attack took place in the same region where where fighters from an ISIS affiliate killed four US special troops and as many Nigerien soldiers in an ambush in October 2017.

Armed groups, including affiliates of al-Qaeda and ISIL, have stepped up attacks on military and civilian targets across West Africa’s Sahel region this year.

The border areas, where Niger, Burkina Faso and Mali meet, are especially dangerous and violence is worsening across the region.

Attackers killed at least 10 in apparently sectarian attacks on churches in neighbouring Burkina Faso this week.

Niger also faces a threat in its southeast from Boko Haram and a splinter group affiliated with ISIL, which are both based in Nigeria but frequently carry out attacks in Niger, Chad and Cameroon.

UNSC discusses Sahel violence

Later on Thursday, representatives from Sahel countries including Niger, Mali, Chad, Burkina Faso, Mauritania were briefing The United Nations Security Council on security in the region.

Reporting from the United Nations, Al Jazeera’s James Bays said ambassadors would likely be shocked by the scale of the growing security challenges in the Sahel.

“We’re talking about instability and violence spreading across an entire region,” he said. “There are countries in this region that used to pretty peaceful a few years ago and they are seeing a great deal of violence.”

“Burkina Faso is one of those countries where there have been attacks recently on churches and Christians and attacks in recent years that have been getting worse and worse,” he said.

“Just last week there was a French special forces operation to free four foreign hostages that were being held in Burkina Faso.”