By Inti Landauro

PARIS--The board of Thales SA (HO.FR) Thursday said the company's general secretary Philippe Logak will become acting chief executive and chairman after Jean-Bernard Levy, the company's top official, left to head French power utility Electricite de France SA (EDF.FR).

The board didn't say how long it will take to fill the position left by Mr. Levy, who was appointed by the French government on Wednesday as CEO of EDF. The government owns about 85% of the utility.

Mr. Levy took over as Thales CEO in December 2012. Mr. Logak was hired as Thales's general secretary in 2013.

The French government owns 26.39% in Thales, while jet-fighter maker Dassault Aviation (AM.FR) owns a 25% stake.

Write to Inti Landauro at inti.landauro@wsj.com

Subscribe to WSJ: http://online.wsj.com?mod=djnwires