Consultants hired by Algeria to value Orascom Telecom's local mobile phone unit are scheduled to complete their work by the end of May, Algerian telecommunications minister Moussa Benhamadi told Reuters.

Algeria's government has said it will nationalise the Djezzy unit after a row with the Egyptian parent company over hundreds of millions of dollars in back taxes and over the unit's ownership.

Uncertainty over how long the nationalisation will take, and how much Algeria will pay for the lucrative unit has hampered a multi-billion-dollar deal for Russia's Vimpelcom to buy Orascom Telecom assets.

Algeria in January appointed law firm Shearman & Sterling LLP to provide a valuation of Djezzy, which has been Orascom Telecom's biggest revenue generator.

The consultancy firm started its work a week ago. The evaluation operation is due to last for three months. Talks will start after the presentation of the results by the firm, Benhamadi said on Wednesday.

Orascom Telecom has said it may be forced to take Algeria to international arbitration unless the dispute over Djezzy is resolved soon.