UPDATE 1-France's Macron pays respects to soldiers killed in Mali, says battle goes on

By John Irish and Tangi Salaün

* 13 French soldiers killed after helicopters collide

* Biggest military loss for France since 1982

* Macron assesses options after 6-year campaign (Recasts with Macron)

By John Irish and Tangi Salaün

PARIS, Dec 2 (Reuters) - President Emmanuel Macron paid tribute on Monday to 13 French soldiers killed in Mali last week and vowed no respite in the fight against Islamist militants in the region.

The soldiers died when their helicopters collided in the dark as they hunted militants. It was the biggest loss of French troops in a single day since an attack in Beirut 36 years ago when 58 soldiers died.

"Thirteen of our bravest soldiers... have died for France and for the protection of the people of the Sahel, for the security of their compatriots and the freedom of the world and us all," Macron said at a ceremony at the Hotel des Invalides also attended by Mali's president.

"In the name of the nation, I bow before your sacrifice," Macron said.

Soldiers stood by the 13 flag-draped coffins holding pictures of the fallen men, who were from four regiments.

Earlier, hundreds of Parisians lined the streets to watch 13 hearses pass through the city centre, escorted by police motorcyclists. Soldiers from their regiments saluted their fallen comrades as they crossed the Alexandre III bridge.

"Too often we forget the sacrifice of these people," said one of the mourners, Alban, a young Parisian whose brother serves in the army. "It's thanks to their dedication that we are free. It's for us that they died."

The deaths highlight the human cost to France of leading a six-year counter-insurgency campaign in West Africa. It has been forced to reassess its strategy, though there is no immediate prospect of withdrawing its 4,500 troops from the region.

France, the former colonial power, is the only Western country with a significant military presence waging counter-insurgency operations in Mali and the wider Sahel, an arid region of west Africa just below the Sahara desert.

"What is at stake in the Sahel is the security of France," Education Minister Jean-Michel Blanquer told RTL radio.

Fifty-eight percent of French people back their country's military mission in the Sahel, an IFOP poll for L'Expansion showed on Monday.

SOLIDARITY

However, security has progressively worsened. Militants with links to al Qaeda and Islamic State have strengthened their foothold, making large swathes of territory ungovernable and stoking ethnic violence, especially in Mali and Burkina Faso.

Macron steered clear of geopolitics in his speech, but made clear the battle would continue.

"(The French forces) stand next to the Sahel armies who are also paying with their blood," he said as Mali's President Ibrahim Boubacar Keita (IBK) looked on.

IBK faced criticism at home on Monday for heading to Paris after not attending a ceremony for the death of 30 Malian soldiers in Gao last month.

"I bow to their memory," IBK said on Sunday in a national address, defending his decision to go to Paris. "We have no reason to bite the hand of those who offer theirs today (to help us)." (Additional reporting Noemie Olive Editing by Gareth Jones)