Thirteen French soldiers who were part of an operation against jihadists in Mali were killed in a helicopter accident on November 25, the French president's office said in a statement on Tuesday.

The accident occurred on Monday evening local time when a Tiger attack helicopter collided with a Cougar military transport helicopter while fighting jihadist fighters in Mali's Sahel. It was the heaviest single loss for French military in nearly four decades.

The helicopters, along with a combat jet, were supporting ground forces as insurgents fled on motorbikes and in pick-up trucks.

Black boxes for the helicopters have been retrieved, French Army Chief Francois Lecointre said. 

French President Emmanuel Macron has sent condolences to the victims' families, the statement added.

"These 13 heroes had just one goal: To protect us. I bow my head in front of the pain of their families and comrades," Macron wrote on Twitter shortly after the statement was issued.

Speaking at a press conference on Tuesday in Paris, French defense minister Florence Parly named the 13 fallen soldiers, saying a one minute national silence will be held later on Tuesday at the National Assembly for them.

Meanwhile the minister also told reporters France will continue its military mission in Mali, aimed at combating terrorism with the support of European allies and joint forces.

"We stand tall, united, resilient. It is this solidarity which strengthens us, which allows us to continue the fight."

France has deployed around 4,500 troops in West Africa's Sahel region as part of Operation Barkhane aimed at combating Islamist militants in the region since its official launch in August 2014.

Before Monday's accident, a number of 38 French soldiers had lost their lives during counter-terrorism operations in Mali since 2013.

(Cover: French President Emmanuel Macron's helicopter is seen as he visits French troops on a counter-terrorism operation in Gao, northern Mali, May 19, 2017. /VCG Photo)