BERLIN — A union representing cabin crew in Germany says it’s expanding a planned strike Sunday at Lufthansa to include employees of the airline’s subsidiaries.

German news agency dpa quoted a Lufthansa spokesman saying the airline would seek to carry out the flights as planned.

UFO said the affected subsidiaries include the airlines SunExpress Deutschland, Lufthansa CityLine, Germanwings and Eurowings.

In addition to calling on members to walk out Sunday between 5 a.m. and 11 a.m., the union said it will also begin balloting members on the possibility of launching an indefinite strike next month.

The union urged travellers to check with airlines about possible delays or cancellations to flights Sunday.