A mysterious tunnel under construction has been discovered near a prison in southern Paris during routine electrical works, although police sources said it did not appear to be part of an escape plan.

The discovery was made on Tuesday by a technician from Enedis, which manages the electricity distribution network in France, who was working “in a well for electrical connections” about 450 metres from La Santé prison, a police source said.

“Bags of rubble and a bed” had been found at the scene, the source added.