A strike by the Verdi union on Wednesday grounded all passenger flights at Berlin Brandenburg Airport (BER) for the entire day.

The walkout began early in the morning as planned and was set to last until midnight, Verdi negotiator Holger Rössler said. Terminals have remained largely empty.

What do we know about the strike at Berlin airport?

"All passengers were informed in good time by their airlines and did not come to the airport at all," said a spokesperson for the airport operator, Berlin Brandenburg Airport Company. "Flights were rebooked or alternative travel options were offered."

According to the operators, around 445 flights affecting approximately 57,000 passengers are impacted.

At least a few passengers did appear to turn up at the airport, apparently unaware of the strike.

Roughly 2,000 employees are taking part, including staff in fire services, air traffic control and terminal management.

Despite some services, such as ground handling and security checks, being run by external providers not involved in the strike, maintaining flight operations has not been possible.

The airport operator criticized the strike as disproportionate, citing already strained conditions linked to the Iran war, while the airport's CEO, Aletta von Massenbach, said she was confident an agreement would be reached at the next round of talks, scheduled for March 25.

State of  Berlin Transport Senator Ute Bonde has urged both sides to move closer and quickly resolve the dispute.

Employers presented an initial offer in the second round of talks last week, but Verdi said it did not go far enough, demanding a 6% pay rise, at least €250 (roughly $290) more per month and an extra day off for union members.