FRANKFURT (Reuters) – German trade union Verdi has asked a court to stop Deutsche Post’s (DPWGn.DE) plans to expand its parcel delivery business by using employees on lower pay deals and has called on workers to stage a strike.

Like other former postal service monopolies in Europe, such as Britain’s Royal Mail (RMG.L), Deutsche Post is seeing its traditional letter business shrink while deliveries of parcels are rising thanks to online retailing.

It announced plans in January to create 10,000 new jobs at its parcel business by 2020, but said new workers would have to accept lower wages than other group employees as it tries to compete in a rapidly growing industry.

Verdi has said such a move would breach an agreement limiting how much business Deutsche Post can outsource to third parties and said it would only accept it if the company shortened its workers’ hours to 36 per week from 38.5.

It said it had filed a suit on Monday with a labour court in Bonn, where Deutsche Post is based, asking for an injunction that would stop the company from going ahead with its plans for the parcel business.

Deutsche Post shares were up 0.3 percent to 29.29 euros by 1128 GMT, and were among the weakest performers in the German blue-cup DAX (.GDAXI), which was up 1.4 percent.

“The workers expect their employer to take their interests seriously and negotiate constructively about our demands for shorter working hours at full pay,” Verdi representative Andrea Kocsis said in a statement.

The union said it would announce details of when and where walkouts would be staged with short notice.

Verdi and Deutsche Post started talks on the matter on Thursday but were unable to reach an immediate agreement. They are due to continue negotiations on April 14.

“We have no understanding for the strike announcement, since the first round of talks just took place a few days ago. And we didn’t immediately reject Verdi’s demands,” a Deutsche Post spokesman said.

The company’s Chief Executive Frank Appel said earlier this month that the new parcel business had already attracted 4,000 employees.

(Reporting by Maria Sheahan; Editing by Georgina Prodhan)