Major strikes in Berlin's two main airports are underway today (13 March) as ground crew refused to clock on in a dispute over pay. Around 660 flights are expected to be cancelled at Tegel and Schoenefeld airports.

The 25-hour strike began at 4am local time (3am GMT)and will run until 5am local time on Tuesday 14 March. The airports have warned that 465 flights will be cancelled at Tegel and 195 at Schoenefeld though these numbers could rise.

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Passengers have been advised to check the details of specific journeys with their airlines. Lufthansa have warned that they will not be operating any flights in either direction between Berlin and Munich, and Berlin and Frankfurt. easyJet, Ryanair and British Airways services are also affected.

Today's walkout is the latest in a series of actions by ground staff who are demanding that their pay be raised to 12 euros (£10.50, $12.80) an hour, according to the Verdi union. On Friday 10 March a similar strike grounded 700 flights.

Around 2,000 employees, including baggage handlers, check-in staff and runway tarmac specialists, earn around 11 euros an hour. Lower offers have been rejected by the union, which is also demanding better working conditions.

Responding to offers by the airport to increase pay incrementally over the next few years, Verdi negotiator Enrico Ruemker said: "The volume is too small and the duration far too long to find a compromise on this basis,"

Passengers travelling in the hours after the strikes may also be subjected to disruption while the airports return to normal service.