On Wednesday the rail operator admitted spying on 173,000 of its 237,000 employees as part of a corruption probe.
"The current explanations are not good enough," unions Transnet and GDBA said in a joint statement, adding that they want Deutsche Bahn to give a more detailed account of the events at a special board meeting. "We expect management to inform the workers who have been spied on,” they added.
On Friday the German government stepped up pressure on Deutsche Bahn boss Hartmut Mehdorn, who told news magazine Focus that neither he, nor the company's management or the board of directors knew anything about the affair.
The magazine added that security companies employed by Deutsche Bahn were responsible for carrying out the surveillance. The intention had been to find any suspect connections which could reveal that bribes were paid in exchange for contracts, according to participants at a closed meeting of parliament's transportation committee on Wednesday.
According to sources close to the committee, Deutsche Bahn pursued investigations in about 100 cases. But no information was leaked about whether any corrupt employees were uncovered.
Deutsche Bahn said in a statement on Wednesday that it did nothing against the law and its "screening" process had been recommended by experts.
The spying scandal comes as Deutsche Bahn agreed to a new deal with the trade unions on pay and working hours to avoid new strikes.
According to an agreement reached late Saturday, 150,000 workers will receive a pay hike of up to six percent over 18 months and at least 12 weekends off work per year, trade union Transnet said.
Unions had staged warning strikes across Germany during the Thursday morning rush hour, causing major disruption for commuters particularly in the south.
The deal includes a 2.5 percent pay hike with immediate effect, another two percent on January 1 and a €500 one-off payment in December. Transnet and fellow union GBDA had pressed for a 10-percent raise.