Bouygues said the move “will have no impact on the Group’s cash position or operating performance.”

The write-down has been prompted by weakness in demand for new thermal power plants.

Bouygues said: “Alstom announced that persistent weakness in demand for new thermal power plants was weighing on its outlook for free cash flow and operating margin.

“This announcement led to a significant deterioration in financial analysts’ cash flow forecasts , an item used by Bouygues to determine the valuations against which it tests the carrying amount of the investment in Alstom in its consolidated financial statements.

“This adjustment will be recognised in the financial statements for the fourth quarter of 2013.

“Bouygues will not recognise any other profit or loss in respect of its investment in Alstom during the fourth quarter of 2013.”

Bouygues is the largest shareholder in Alstom with a 29.5% stake.