The makers of TGV and ICE high-speed trains agreed last September to merge their rail operations to create a European champion capable of fending off the challenge of China's state-owned CRRC Corp Ltd.

The two sides resolved delicate issues of governance by handing ownership and board control to Siemens, the German conglomerate, while naming Alstom boss Henri Poupart-Lafarge to run the venture.

Gabriel, 58, was among six of 11 directors designated by Siemens, whose chief technology officer Roland Busch will be chairman of the board.

Poupart-Lafarge will also serve as a director along with four independent members proposed by Alstom.

Gabriel's move follows a political career in which he served as economy and foreign minister, and as vice chancellor. He stood down as leader of the Social Democratic Party in early 2017.

The party went on to its worst post-war showing in last September's general election but, after months of negotiations, agreed to return to government with Chancellor Angela Merkel's Christian Democrats.

The board nominations are subject to the approval of Alstom's shareholders and will become effective when the joint venture deal is completed, Siemens and Alstom said in a joint statement.

(Reporting by Douglas Busvine. Editing by Jane Merriman)