"We are working on several measures to improve the situation," Fraport Chief Financial Officer Matthias Zieschang told analysts on Wednesday, adding waiting times at Frankfurt's main terminal had hit 40 minutes at peak times, compared with a target for 10 minutes.

Fraport will add an additional 3 security lanes in Terminal 1 shortly by reorganising the existing layout, plus a further 10 lanes for next year by constructing a small building next to Pier A-Plus at a cost of about 10 to 15 million euros (8.7-13 million pounds).

That will increase the number of security lanes to 28 from 15 now, Zieschang said during a presentation on first quarter results, adding Fraport was also working on motivating staff to work harder and more quickly.

Lufthansa CEO Carsten Spohr has criticised Fraport for the delays at security checks.

The delays are hurting Fraport's retail revenue too. Despite a 10 percent increase in passengers at Frankfurt in the first three months of the year, the number of shoppers dropped 3 percent, partly due to the security check bottlenecks, Zieschang said.

Retail revenue per passenger at Frankfurt fell to 3.31 euros in the first quarter from 3.86 euros one year ago, also hit by currency effects and more passengers on short-haul flights, who typically do not shop in duty free.

(Reporting by Victoria Bryan; Editing by Maria Sheahan)