Fraport's January passenger numbers at its main Frankfurt Airport slid by around 6 percent in January, according to Annegret Reinhardt-Lehmann, spokeswoman for Fraport's marketing division.

The decline was steeper than the 5.3 percent slump booked in December, and would likely lead to a first-quarter fall of around 7 percent, she said citing preliminary figures.

Airlines and airport operators such as Fraport have been hit by fallout from the financial crisis as companies spend less on business travel and consumers tighten their purse strings.

According to Ralf Teckentrupp, president of German airlines' association BDF, demand for passenger air travel in Germany is currently down 10 percent, partially because consumers are delaying bookings until closer to their planned departure date.

Nonetheless, the expected decline in passenger numbers at Frankfurt in 2009 would not be as bad as the 4.7 percent slump during the Gulf war of 1991, the worst decline the airport has seen in recent years, Reinhardt-Lehmann said.

Fraport management board member Stefan Schulte said last week he saw the aviation business reaching its trough in the first quarter and recovering in the second half of this year as weak figures from the end of last year form an easier basis for comparison.

Fraport has been expanding outside its German home market to tap into growth abroad and has stakes in airports at Lima, in Peru, and Xian, in China.