FRANKFURT (Reuters) -Thyssenkrupp on Thursday said its supervisory board approved a planned sale of 20% of the conglomerate's steel division to Czech billionaire Daniel Kretinsky in the face of continued opposition from labour representatives.

The German industrial group said that labour leaders, who hold half of the non-executive board's seats, voted against the deal. Board Chairman Siegfried Russwurm's vote was counted twice, which is allowed under German corporate governance laws to break a stalemate.

Shop stewards warned last week they might oppose the deal unless there were written assurances regarding jobs and sites.

Approval of the partial sale marked a key step in Thyssenkrupp's path to what it hopes will be a 50/50 steel joint venture with Kretinsky, whose energy holding EPCG would help lower electricity costs, a major factor in steelmaking.

Earlier this month, Thyssenkrupp cut its 2024 guidance for the second time in three months, highlighting troubles in the steel business, which has been hit by lower demand and prices.

Juergen Kerner of trade union IG Metall, who is deputy board chairman, said labour leaders in principle welcomed Kretinsky's willingness to invest in the business but the stake sale amounted to a rushed separation of the steel unit from the parent company.

"This will be met with fierce opposition by us," said Kerner.