Security personnel at Berlin's Tegel and Schönefeld airports have begun a four-hour strike, causing flight cancellations and delays in the German capital, reported DW. 

Personnel walked off the job at 5 a.m. (0400 UTC), in a warning to the Federal Association of Aviation Security Companies (BDLS), said Germany's largest trade union, Verdi.

About 60 Flights at Tegel and 20 at Schönefeld have been affected by the strike, which is expected to lead to delays and missed connections throughout the day.

Tegel and Schönefeld have warned of "severe disruption" and called on passengers traveling on Monday to contact airlines to check the status of particular flights.

'Completely inadequate offer'

Verdi's decision came after BDLS put forward what union officials said was a "completely inadequate offer" in talks over wage increases for 23,000 airport security personnel across Germany just before Christmas.

The union is demanding an increase in the hourly wage to €20 ($22.79) for staff working in passenger, freight, personnel and goods control at all German airports. An employee working in passenger control at one of the two Berlin airports currently receives €17.12 per hour.

The next wage talks between Verdi and BDLS are scheduled for January 23.

A breakdown in negotiations may lead to strikes at other German airports, Verdi said.