Nigerian telecoms firm Starcomms said on Wednesday its core earnings (EBITDA) had more than quadrupled to 6.74 billion naira ($45 million) in the nine months to the end of September.

Nigeria's biggest fixed wireless operator said a 60 percent increase in its subscriber base -- which pushed revenues up five percent to 25.62 billion naira in the period -- and cost cutting had contributed to the rise in profits.

Given the challenging economic climate, rising fuel prices and the fierce level of competition initiated by other CDMA operators, I am pleased with the company's performance, Chief Executive Maher Qubain said in a statement.

But Starcomms said unrealised foreign exchange losses due to a depreciation in the value of the local naira currency NGN= had contributed to a 1.1 billion naira pre-tax loss in the third quarter.

It said it had converted $60 million of its dollar-denominated debt into a medium-term naira facility which would reduce its exposure to exchange rate fluctuations.

(Reporting by Chijioke Ohuocha; Editing by Nick Tattersall)