Jan 21 (Reuters) - Soitec's plan to appoint a new CEO has the "full support" of its main shareholders, the French semiconductor company said on Friday, after the company's executive committee questioned the decision.

Following Pierre Barnabé's appointment as CEO on Wednesday, the executive committee sent a letter to the board of directors, seen by Reuters, describing the move as "incomprehensible" given the progress made by current CEO Paul Boudre.

"The chosen successor of Paul Boudre, Pierre Barnabé, has the necessary skills and experience to lead Soitec as Chief Executive Officer for the next phase of growth towards our ambitious objectives," the group responded in a press release.

Barnabé, who is senior EVP, Group Security Officer and Global Head of Big Data and Cybersecurity at Atos, is due to join the company on May 1 and take over as CEO at the end of the July 2022 shareholders' meeting.

Shares in Soitec slumped around 17% on Thursday, their worst day since December 2014.

Soitec's four main shareholders, each with stakes of about 10%, are National Silicon Industry Group, Bpifrance, BlackRock Financial Management and CEA Investment, according to Refinitiv data. (Reporting by Kate Entringer in Gdansk Editing by Mark Potter)