Berlin  -  Deutsche Bahn, the government-owned German railways company, approved Thursday a plan to sell a quarter-stake in its operating business later this year to private investors, but labour groups said they had won a rider blocking any lay-offs.

The autumn was now a feasible time to float the shares, said chief executive Hartmut Mehdorn after DB's supervisory board had signed off on the project after months of wrangling with the government and trade unions.

But two main rail unions, Transnet and GDBA, who have representatives on the board, said they had secured labour guarantees. The unions had demanded a promise of no dismissals before 2023 and a corporate structure that obstructs low-pay employment.

Conversely, those terms could dismay investors who will be offered a 24.9-per-cent stake in the operating company, but not in the 34,000 kilometres of tracks, the stations or the electricity plants. The infrastructure will remain federal property.

The limitation of the stock sale to 24.9 per cent and not more was at the insistence of Social Democrats in Christian Democratic Chancellor Angela Merkel's coalition government in Berlin.

The sell-off is expected to raise about 6 billion euros (9.5 billion dollars) which will partly fund investment.

A Transnet spokesman said the labour contract had been signed early Thursday before the board meeting. The two unions said their demands had been met, but gave no immediate details. (dpa)