The death toll after two buildings collapsed in the Marseille this week has risen to five, the southern French city's fire service said on Wednesday.

As efforts to find further victims or survivors continued, broadcaster France Info quoted local prosecutor Xavier Tarabeu saying that there were likely three more people trapped under the rubble.

Rescuers were "working away like we did from the start. With our shovels, with our hands, we're digging away," Marseille fire chief Admiral Charles-Henri Garie told the broadcaster.

Local newspaper La Provence reported that rescuers had placed laser detectors on two more adjoining buildings in case they too started to collapse.

Two neighbouring buildings, one derelict and the other still occupied, collapsed on Monday morning and rescuers later pulled down a third adjoining building that was in a dangerous condition.

One of the buildings that initially collapsed, at no. 63 rue d'Aubagne, was derelict and apparently empty, but the other, at no. 65, was occupied.

Anger was reported to be growing locally over the situation, after city authorities confirmed that no. 65 had been inspected in mid-October.

Remedial works had been carried out under the supervision of an expert appointed by judges to allow its residents to return, city authorities wrote on Twitter.

In a video posted online by La Provence, two tenants recounted how they had decided to leave the building in recent days after seeing walls subside or doors become jammed.