Hollande, president from 2012 to 2017, was attending a France-Germany football friendly on the night of November 13, 2015 at the Stade de France stadium in Paris when the first bomber detonated his vest, prompting security agents to whisk him away as two more blasts went off.

Gunmen later opened fire on cafes and restaurants in a lively part of the capital and stormed the Bataclan concert hall, killing indiscriminately and taking hostages.

Hollande quickly went on TV to speak of the “horror” still unfolding, which by the end of the night left 130 people dead, and he later declared a state of emergency.

Details remain murky on how many of the assailants or associates entered and remained at large in Europe despite being on the radar of intelligence services.

That has prompted some of the victims’ families to wonder whether the bloodshed could have been prevented.

France had already been on high alert for jihadist attacks since the massacre of 12 people at the satirical Charlie Hebdo newspaper and of four others during a hostage-taking of a Jewish grocery store over three harrowing days in January 2015.

Life for Paris, a victims’ association that is one of several plaintiffs in the November 2015 attacks trial, called for Hollande to testify as a witness over his government’s efforts to counter the jihadist threat.

Several of the 10 attackers slipped into Europe from Islamic State strongholds in Syria, using fake passports and blending in with streams of migrants fleeing war and poverty.

All were killed or eventually gunned down by police except for Salah Abdeslam, a dual French-Moroccan national, who was captured in Brussels after discarding his suicide vest.

But several had been known to intelligence agents or under surveillance in France, Belgium and elsewhere, including an alleged ringleader of the attacks, Abdelhamid Abaaoud.

A prominent French-speaking jihadist in Syria with a past role in several foiled attacks in France, Abaaoud was killed in a huge police raid in the northern Paris suburb of Saint-Denis on November 18.

Associates of the attackers had also been on the radar of European security forces, fuelling questions about whether intelligence agencies missed or mishandled key information that could have helped prevent the attacks.

“Francois Hollande knew the risks he was taking in attacking the Islamic State in Syria,” Abdeslam has said during the marathon trial that began in September.

He was referring to Hollande’s decision to authorise French airstrikes against the group in Syria, as part of the US-led coalition to oust the jihadists from territory they had seized in a bid to create an Islamic “caliphate”.

But so far Abdeslam has refused to provide investigators with details about the operational planning.