The European Union has called for an investigation into the reported killing of around 100 people in Burkina Faso earlier this week.
"Around 100 civilians, including women and children, were believed killed in a massacre," said foreign policy chief Josep Borrell in a statement.
The United States has also condemned the attack.
It is not clear who was behind the 6 November attack in the village of Zaongo.
Mr Borrell called on Burkina Faso's military junta to shed light on the circumstances of the deaths. It has not yet responded.
Burkina Faso is trying to contain a jihadist insurgency that spread from neighbouring Mali.
The military government has been forcing civilians to join the fight against the Islamist groups, who are said to control about 40% of the country.
About a quarter of Burkina Faso's schools have been forced to close because of the insurgency, according to aid agencies.
One resident told the AFP news agency that Zaongo was one of the few villages in the area not to have been "emptied out by the terrorists".
"Some suspected the inhabitants of collaborating with them," the resident said.
The army seized power last year vowing to stop the jihadist attacks. If anything, the number of deaths has since increased.
Last year was the country's most deadly on record, according to the US-based Armed Conflict Location & Event Data Project (Acled), with more than 1,400 civilian deaths.
So far this year, almost 8,000 people have been reported killed due to violence in the country, Acled says.