This article is more than 10 months old

This article is more than 10 months old

Gunmen in Burkina Faso have killed nearly 40 civilians in an ambush on a convoy transporting workers for the Canadian goldminer Semafo, regional authorities have said.

The attack on Wednesday underlines the growing instability in the Sahel, where Islamist extremist groups have grown in influence and power over the past decade.

Semafo said in an earlier statement that the attack on a convoy of five buses with a military escort took place on the road to its Boungou mine in the eastern region of Est, about 40km (25 miles) from Boungou, and that there had been several deaths and injuries.

Nineteen of the people killed were employees of an Australian company, Perenti Global Ltd, which had been contracted by Semafo. Perenti saidin a statement that another 20 employees had been injured.

The Est governor’s office later gave more details, saying “unidentified armed men laid an ambush for a convoy transporting Semafo workers”, giving a provisional civilian death toll of 37 with more than 60 wounded.

An unknown number of security force personnel may have also been killed in the attack, and officials said the number of casualties was likely to rise as a large number of people were unaccounted for.

Two other security officials said the military vehicle leading the convoy was struck by an improvised explosive device on a stretch of road where there is no mobile phone network. Shortly after the explosion, an unknown number of gunmen opened fire. One of the sources said they appeared to target the buses as well as the military escort, which was unusual.

In December, a police vehicle was attacked on the same road, resulting in five deaths. The latest attack is the deadliest in recent years as the military struggles to contain Islamist violence that has overrun parts of Burkina Faso.

After incidents last year, which Semafo said were the work of “armed bandits”, the company reinforced its escorts and decided to transport all expatriate employees by helicopter between the Boungou mine and Ouagadougou, the capital.

Burkina Faso, once a pocket of relative calm in the Sahel, has endured a homegrown insurgency for several years, amplified by the spillover of jihadist violence and criminality from its chaotic northern neighbour, Mali.

Attacks by Islamist militants – typically hit-and-run raids on villages, road mines and suicide bombings – have claimed nearly 700 lives in Burkina Faso since early 2015 and forced almost 500,000 people to flee their homes.

Burkina Faso’s previous deadliest attack was in January 2016, when jihadists raided a hotel and a cafe in Ouagadougou, killing 30 people, about half of them foreign nationals.

In August, 24 soldiers were killed in an assault on a base in Koutougou.

On Monday, an attack on a base in northern Burkina Faso killed at least five military police officers and five civilians.

The attacks have been claimed by a range of jihadist groups, including al-Qaida and Islamic State.

Earlier this year, US military officials warned that the rapid and alarming deterioration of the security situation in Burkina Faso was threatening the destabilisation of a vast area of west Africa.

There are daily attacks across the Sahel and parts of west Africa. At least 10 Nigerian troops were killed in a jihadist ambush on their convoy in the restive north-eastern region. Another 12 soldiers are missing after the patrol was attacked on Wednesday in Borno state.

Burkina Faso’s poorest areas in the north and east have been neglected, with the government providing minimal health services, education, jobs and infrastructure. Locals have in response forged links with militant groups – who promised, and delivered, more services than the state – and have taken up arms.

The country’s badly equipped, poorly trained and underfunded security forces have been unable to stem the violence, which has intensified throughout this year to become an almost daily occurrence.

Part of the state security forces’ response has been to summarily execute suspects and make mass arbitrary arrests, according to Human Rights Watch, with those targeted usually ethnic Fulani herdsmen. Fulanis, who have little access to education or political influence, are frequently scapegoated as jihadists, with often deadly results; up to 200 were massacred in early January.