FRANKFURT, May 10 (Reuters) - Germany airport operator Fraport reported better-than-expected sales on Tuesday as travel demand boomed in the first quarter, but it posted lower-than-expected profits after a writedown related to its St. Petersburg subsidiary.

Fraport said its earnings before interests, taxes, depreciation and amortisation (EBITDA) rose 75% to 70.7 million euros ($74.77 million), below the 85 million euros expected by analysts in a Refinitiv poll.

This was because it had to write down 48.2 million euros on a loan connected with its minority-owned St. Petersburg subsidiary due to increased default risk amid the war in Ukraine, Fraport said.

The group's revenue rose 40% to 539.6 million euros, above analysts' average forecast for 515.8 million euros. ($1 = 0.9456 euros) (Reporting by Zuzanna Szymanska; Editing by Maria Sheahan)