Cairo-based Orascom Telecom reported a net loss of $468.9 million before minority interests in the fourth quarter, up from a loss of $123.5 million a year earlier.
In a statement on Wednesday the company also reported a full-year loss of $205.76 million, compared with a profit of $660.35 million in 2011.
It said the deterioration was driven by tax charges, foreign exchange losses and other financial problems.
Orascom Telecom, which is controlled by Russia's Vimpelcom , said its fourth-quarter revenue stood at $908.34 million, up from 895.71 million a year earlier.
Earnings before interest, tax, depreciation and amortisation (EBITDA) rose 23 percent to $425.50 million, while subscriber numbers reached 84.92 million, up 8.7 from the fourth quarter of 2011.