UPDATE 1-Canwest to sell four Turkish radio stations

* Value of deal with Spectrum Medya not disclosed

* Proceeds will be used to pay down debt

* Deadline looms in negotiations with creditors (In U.S. dollars unless noted)

TORONTO, May 15 (Reuters) - Canwest Global Communications Corp CGS.TO, Canada's biggest media company, is selling its indirect interests in four Turkish radio stations as it fights to shore up its debt-laden balance sheet.

Canwest, which owns Canada's Global television network and a chain of daily newspapers, did not disclose the value of the deal with Spectrum Medya, a Turkish-based company.

It said the proceeds will be used to pay down debt outstanding under a credit facility of its main subsidiary.

Winnipeg, Manitoba-based Canwest's decision to sell the stations comes just days before a May 19 deadline in negotiations with its creditors and noteholders.

Canwest already owes a $30.4 million interest payment to the noteholders, who now also have the right to demand the payment of about $761 million in principal. However, the investors have agreed not to do this while talks continue.

While critical, the missed interest payment is only the tip of the iceberg for Canwest, which has a debtload of close to C$4 billion ($3.4 billion), some of it dating back to its 2000 acquisition of newspaper assets from Hollinger International.