(Photo: chinanews.com)

A German labor union is calling on security staff at three German airports to stage a strike Thursday amid ongoing pay negotiations.

The ver.di union said Wednesday that it's urging workers to join a one-day walkout that is likely to cause disruptions for airline passengers.

The strike will affect airports in Duesseldorf, Koeln-Bonn and Stuttgart.

Security staff at Berlin’s two airports already staged a strike Monday that caused severe disruption to flights.

The union wants hourly pay for all workers conducting security checks to rise to 20 ($22.81) euros. The employers association BDLS says this could amount to an increase of 30 percent in some cases.