ISTANBUL - Turkish airport operator TAV said its first quarter loss increased by 12 percent to 61.9 million lira ($39 million), due partly to the cost of financing the construction of an airport in Tunisia.

The loss compares with a first-quarter loss of 55.2 million lira last year, TAV said in an income statement posted on the stock exchange's Web site late on Friday. The Istanbul-based company said its first quarter sales rose 70 percent to 459.5 million lira.

The leap year effect, decreasing the February result by 3.5 percent, along with the global economic crisis lowered our first quarter 2009 results, Chief Executive Sani Sener said in an e-mailed statement. Our ongoing investment in Tunisia resulted in a negative cash flow.

In euro terms, TAV said its loss declined to 28.7 million euros in the first three months from 30.4 million euros a year ago. Sales in euro terms fell 6 percent to 113.5 million euros.

TAV is building an airport in Enfidha, Tunisia, that is due to be completed in October. TAV also operates three terminals in Turkey, the Tbilisi and Batumi airports in Georgia and another airport in Tunisia.

TAV's passenger numbers in the first three months of the year were flat at 7.9 million, compared with a year ago, Sener said.

(Reporting by Ayla Jean Yackley; Editing by Ruth Pitchford)