Thousands of people have joined a silent march in the southern French city of Nice in memory of Herve Gourdel, the hiker beheaded last week by Algerian militants linked to the Islamic State group.

Gourdel was seized on September 21 by the IS-linked group Jund al-Khilifa, or “Soldiers of the Caliphate”, while trekking in a national park in northeastern Algeria.

His beheading, which was posted online in a video Wednesday after France rejected the kidnappers’ ultimatum to halt anti-IS air raids in Iraq, drew an outpouring of grief and fury in France.

Carrying 2000 posters of Gourdel and 1000 white roses, the cortege of family, friends and well-wishers on Saturday wove through Nice, the 55-year-old’s hometown, to an open-air theatre where a fellow mountain guide paid homage to him.

“We will hold on to the indelible memory of your friendship,” Michel Bricola read out in a choked voice, surrounded by a dozen fellow mountaineers.

France is flying flags at half-mast in honour of the mountaineer, who had trained Moroccan mountain guides and worked in the southern Alps.

His murder came after three other Western hostages — two US journalists and a British aid worker — were beheaded by IS.

The beheading drew outrage from prominent French Muslims, who led a rally Friday in Paris against jihadi violence. Anti-racism and left-wing groups have also called for a further demonstration in Gourdel’s honour on Sunday.