Earlier strikes resulted in the cancelation of hundreds of flights at Duesseldorf, Cologne-Bonn, Stuttgart and Berlin’s two airports BERLIN: A German labor union is calling on security staff at Frankfurt airport to go on strike next week in a dispute over pay. The ver.di union said Friday that workers should walk out at Germany’s biggest airport between 2 a.m. and 8 p.m. (0100-1900 GMT) Tuesday. The union said it couldn’t rule out other airports being affected by walkouts. Ver.di says it’s still waiting for employers to put forward a negotiable offer for some 23,000 security staff. Earlier strikes resulted in the cancelation of hundreds of flights at Duesseldorf, Cologne-Bonn, Stuttgart and Berlin’s two airports in recent days. The union wants hourly pay for all workers conducting security checks to rise to €20 ($23.10). Employers association BDLS says this could amount to a 30-percent increase in some cases.