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 its 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.

"The process, which began in March 2021, was conducted in complete conformity with best-practice governance standards and with the full support of Soitec’s main shareholders," it added.

A spokeswoman for Bpifrance, French state shareholder with a 10.35% stake, declined to comment on Friday, but referred to comments the day before by its chief executive in a interview with BFM Business.

In that interview, CEO Nicolas Dufourcq expressed surprise at the executive committee's reaction and said the process was conducted in a "completely normal" way.

Paris-listed shares in Soitec were up 1% at 0930 GMT, after plunging as much as 19% on Thursday, their worst day since December 2014.

Soitec's three others main shareholders, each with stakes of about 10%, are National Silicon Industry Group, BlackRock Financial Management and CEA Investment, according to Refinitiv data.

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.

Chairman Eric Meurice and CEO Boudre "are committed to working together to ensure a smooth leadership transition enabling successful execution of Soitec's 2026 strategic plan," the group said. (Reporting by Kate Entringer in Gdansk Additional reporting by Blandine Hénault in Paris Editing by Mark Potter)