Bamako: Gunmen killed at least eight Chadian UN peacekeepers in an attack on Sunday on one of their bases in northern Mali, multiple sources reported.
The UN spokesman in Mali condemned what he described as a vile and cowardly attack and called for a "robust" response.
"According to a new toll, still provisional, at least eight peacekeepers have been killed," a source close to the MINUSMA force said.
The attack happened early on Sunday at the Aguelhok base 200 kilometres (125 miles) north of Kidal and towards the border with Algeria, the source added. A diplomat in northern Mali said that several of the attackers had also been killed.
Mahamat Saleh Annadif, the UN's special representative for Mali, condemned the attack in a statement.
"Peacekeepers of the MINUSMA force at Aguelhok fought off a sophisticated attack by assailants who arrived on several armed vehicles," he said.
The "cowardly" attack, he added, "illustrates the determination of the terrorists to sow chaos.
"It demands a robust, immediate and concerted response from all forces to destroy the peril of terrorism in the Sahel."
An attack at the same base last April killed two peacekeepers and left several others wounded.
More than 13,000 peacekeepers are deployed in Mali as part of a UN mission that was established after militias seized northern Mali in 2012. They were pushed backed by French troops in 2013.
A peace agreement signed in 2015 by the Bamako government and armed groups was aimed at restoring stability to Mali following a brief takeover in the north by militants.
But the accord has failed to stop violence by militants, who have also staged attacks in neighbouring Burkina Faso and Niger.
Earlier this month, both France and the United States criticised the authorities in Mali for their failure to stem the worsening violence.
On January 16, France threatened to push for more targeted sanctions to be imposed on Mali after hearing a UN official report on worsening violence in the West African country.
And Washington renewed its warning that it would push for changes to the peacekeeping mission in Mali, possibly a major drawdown, if there was no progress.
In August, a panel of experts said in a report to the UN Security Council that inter-communal conflicts in the region were exacerbating existing tensions from clashes between extremists groups and international and Malian forces.
On Sunday, France's Defence Minister Florence Parly told French radio that the G5 Sahel anti-jihadist force in the region was in the process of resuming operations.
They were suspended after an attack on their headquarters in mid 2018. The countries working in the G5 force comprise Mali, Mauritania, Niger, Burkina Faso and Chad.