France to drain lake under Mont Blanc glacier

French engineers are set to drain a lake that has formed under a glacier on Mont Blanc and threatens to flood the St Gervais valley.

The lake, which is said to contain 65,000 cubic metres (2.3m cubic ft) of water, was discovered last month during routine checks.

In 1892 water from an underground lake flooded the Saint Gervais valley killing 175 people.

Christian Fraser reports.