German trade union Verdi on Wednesday called on workers at Frankfurt, Munich, Stuttgart, Hamburg, Dortmund, Hanover and Bremen airports to go on a 24-hour strike, saying collective bargaining efforts had made little progress.

"On Friday, February 17, 2023, there will therefore be massive disruptions to air traffic," said Fraport (FRAG.DE), the operator of Frankfurt airport, which counted more than 48 million passengers in 2022.

It urged travellers to avoid the airport that day.

The strike is expected to affect domestic travel in particular, according to Verdi, which said it had given advance warning about the strike so passengers could find alternatives.

The walkout also coincides with the start of the 59th Munich Security Conference (MSC), which brings hundreds of delegates to the Bavarian capital, including several global leaders.

Munich airport, Germany's second-biggest, said there would be no regular passenger flights on Friday but special flights, including those for the MSC would not be affected.

However, an MSC spokesperson said the strike would have an effect on the conference schedule, adding that organisers were in close contact with all parties to minimise the impact.

The union is currently in negotiations for three groups of workers: ground service staff, public sector officials and aviation security workers.

"There is still a catastrophic shortage of workers in ground services - this was clearly felt by travellers last summer," Verdi board member Christine Behle said in a statement.

Airlines across Europe have faced labour strife since last year as the rapid recovery in tourism led to staff shortages and soaring inflation prompted employees to demand higher wages.

The new year brought with it fresh action in Germany as a walkout organised by Verdi at Berlin airport, which is not directly affected by Friday's strike, led to the cancellation of all flights on Jan. 25.