Mobile TeleSystems (MTS), one of Russia’s top three mobile operators, has posted a U.S. GAAP net profit of $362mn in the third quarter of 2011, down almost 25% from $484mn in the same period of last year.

The decrease was due to “depreciation of the Russian rouble versus the U.S. dollar, which resulted in a non-cash foreign exchange loss of $191mn,” the company said in a statement.

The company’s revenue rose 13% in July-September, to $3.275bn.

MTS’s Operating Income before Depreciation and Amortisation (OIBDA) in the reporting period rose 9% to $1.452bn, while its capital expenditures stood at $704.3mn or 21.5% of the company’s overall revenue.