WASHINGTON, March 20 (Reuters) - General Motors Co Chief Executive Mary Barra is scheduled to testify on April 1 to a U.S. House of Representatives panel investigating the company's long-running problem with defective ignition switches that have been linked to 12 deaths, the committee said on Thursday.

House Energy and Commerce Committee leaders also said they had invited National Highway Traffic Safety Administration acting Administrator David Friedman to testify at the hearing.

(Reporting by Richard Cowan; Editing by Peter Cooney)