Updated

Thousands of air travelers are stranded in Germany after security personnel walked off the job at two airports in a wage dispute.

Security workers at Hamburg and Cologne airports went on strike Friday, causing more than 200 flights to be canceled at the airports.

The country's main hubs, Frankfurt and Munich, were not affected.

The ver.di union called the strike after the latest round of negotiations with employers ended last week without an offer they found acceptable.

Airport workers in recent months have staged several such daylong "warning strikes," which are often used to increase pressure in German wage negotiations.

The union seeks a roughly 30 percent pay increase for the private security workers. Employers have offered a 9 percent raise.