German airline Lufthansa said on Friday it is considering taking legal actions against a warning strike as a full day walkouts scheduled for next Monday will affect airports across the country and cost the airline tens of millions of euros.A Lufthansa spokeswoman told local media that the union Verdi called for a one-day strike at almost all airports in Germany, which could no longer be described as a warning strike.Representing 33,000 workers of the Lufthansa, Verdi union is in a collective bargaining with the airline for a salary increase of 5.2 percent and a more secure job condition.In a statement issued on Friday, Verdi called on Lufthansa employees to stage full-day warning strikes at German airports on April 22 after management failed to come up with a negotiable pay offer in the third round of talks on April 17.Air traffic will be affected on Monday in big German cities including Berlin, Frankfurt, Hamburg, and Munich.Lufthansa earlier said there would be delays and cancellations on Monday due to the planned strike, adding that the airline would put necessary measures into place.Hundreds of Lufthansa flights were cancelled on March 21 due to a nationwide strike in major German airports.