(Adds claim of responsibility from Islamic State, background)
NIAMEY, May 16 (Reuters) - Islamic State’s West African branch on Thursday claimed responsibility for an ambush that killed 28 soldiers this week in Niger, as the militant groups seek to establish roots in the impoverished Sahel region.
Tuesday’s ambush occurred near the town of Tongo Tongo, where fighters from an Islamic State affiliate killed four U.S. special forces and four Nigerien soldiers in an ambush in October 2017.
Government soldiers were pursuing gunmen who had earlier attacked a high security prison, when one of their vehicles rode over a mine and they came under fire, government spokesman Abdourahamane Zakaria told Reuters.
The claim of responsibility was translated into English and published on the SITE Intelligence website.
Islamist militants loyal to Adnan Abu Waleed al-Sahrawi, the leader of Islamic State in the Greater Sahara, operate along Mali’s border with Burkina Faso and Niger, in the vicinity of Tuesday’s attack.
The other regional group claiming allegiance to Islamic State — IS West Africa Province or ISWAP — is based more than 1,000 miles away, in southeast Niger.
The attack, one of the deadliest against the military in Niger’s west in recent years, marks a major setback for military operations trying to restore order in a region plagued by jihadist groups and allied criminal gangs.
Despite years of heavy deployments of French, U.S. and U.N. forces, Africa’s Sahel region remains a tinderbox of Islamist fighters, ethnic militias and criminal smuggling rackets.
The border areas where Niger, Burkina Faso and Mali meet are especially dangerous and violence is worsening across the region. Gunmen suspected to be Islamists killed at least 10 in apparently sectarian attacks on churches in neighbouring Burkina Faso this week. (Reporting by Moussa Aksar in Niamey Additional reporting by Hesham Hajali in Cairo Writing by Tim Cocks and Edward McAllister Editing by Gareth Jones and Catherine Evans)