Lufthansa has signalled it will not give in to the demands of pilots as they begin their 13th strike in 18 months.

The German carrier said it was "determined" to get its way, following the breakdown of talks last week aimed at resolving the long-running dispute.

What began as a row over retirement benefits has escalated to take in other issues including Lufthansa's plans to expand its low-cost Eurowings brand - and has cost Germany's largest carrier at least €100m in lost revenue this year alone.

The pilots' union said it was extending Tuesday's 16-hour stoppage into a full day of action on Wednesday, which would affect short-haul flights on both Lufthansa and Germanwings services.

Lufthansa said half its long-haul services planned for Tuesday from Frankfurt, Munich and Dusseldorf had been axed and it expected to confirm later on Tuesday that several hundred services would have to be cancelled the following day.

Cargo flights have also been hit.

The union, Vereinigung Cockpit, has threatened further industrial action this week.

Its spokesman Markus Wahl added that "strikes are possible in the following weeks as well."

One of the major sticking points concerns Lufthansa's bid to extend its low-cost operations abroad.

While the company argues it must cut costs to better compete with budget rivals across Europe, the union has demanded the company stops moving jobs out of Germany.

(Sky News)