Turkey's largest mobile phone operator Turkcell said on Tuesday it had placed a non-binding preliminary bid to buy Bulgarian mobile operator Globul, put up for sale by its owner, Greece's OTE.

The Istanbul-based company, in a statement to the Istanbul Stock Exchange, said it placed the bid as it explores investment opportunities in the region.

Globul, Bulgaria's second-biggest mobile operator, reported earlier this month a sharp decline in revenues in a worrying sign about the future deal.

The revenues of telecoms operator Globul have dropped 20.9% in the third quarter of the year on an annual basis to EUR 85.9 M, data shows.

OTE, the biggest telecoms operator in southeastern Europe, announced in mid-June it plans to sell its Bulgarian units to help refinance EUR 3.4 B debt maturing in the next two years.

According to unconfirmed reports, OTE has hired the London unit of US Citigroup as a consultant for the sale.

Greek telecoms group OTE will seek to sell its Bulgarian businesses - a mobile phone company and an electronic appliance retail chain Germanos - for no less than EUR 800 M, according to reports.

Deutsche Telekom, which controls a 40% stake in OTE, Turkish Turkcell, British Vodafone and Orange, owned by France Telekom, have been listed as potential buyers.

Globul is the trademark under which Cosmo Bulgaria Mobile EAD offers mobile telecommunications services in Bulgaria.

The company is 100% owned by Cosmote, OTE's mobile phone arm.