The weakening rouble, coupled with higher interest expenses, led profits at Russian fixed-line telecoms operator Comstar to drop over a quarter between July and September, it has emerged.

According to data released by the company, which has given a more bullish outlook for revenue growth in rouble terms, net profit in 2009's third quarter fell by 26 per cent to $26.9 million. That compares to profits of $36.4 million in the same period last year.

The drop, which was steeper than analysts predicted, reflects rouble depreciation which occurred at the turn of the year.

In a statement, Comstar, recently taken over by mobile operator OAO Mobile TeleSystems, confirmed: "The significant weakening of the Russian rouble against the US dollar since September 2008 adversely impacted the group's US dollar reported results."

While Comstar's interest expenses doubled to $29 million from a year earlier, the company recorded $4.3 million in foreign exchange losses against a $4.5 million forex gain in 2008's third quarter.

In recent months, a drop in Russian automobile sales was also blamed on the weakening rouble. The country's imported car market is said to have been further damaged by a 30 per cent import duty.