ANKARA, Turkey — Turkey's procurement authorities have decided to release a request for proposal, to be sent to three local armored vehicles manufacturers, as part of the Altay tank program.

This decision effectively means the three companies will be invited to bid on the program, estimated to reach beyond $10 billion.

The companies that received the RFP from the Undersecretariat for Defence Industries, or SSM, are BMC, Otokar and FNSS, all privately owned companies.

In June, SSM decided to scrap sole-source negotiations with Otokar for the Altay program. Otokar is the developer and builder of prototypes of the Altay, Turkey's first indigenous new-generation main battle tank.

The Altay contract involves the serial production of an initial batch of 250 Altay tanks. Turkey plans to manufacture a total of 1,000 units. 

Rarlier this year, Otokar's Altay prototypes successfully completed qualification tests including mobility and endurance testing on rough terrain and climatic conditions, firing tests with various scenarios, and survivability testing. In 2008, Otokar, Turkey's largest privately owned defense company, had signed a $500 million contract with SSM for the development and production of four prototypes of the Altay.

But in June, the government agency, citing an unsatisfactory offer from Otokar for the serial production of the tank, canceled the contract and decided to go for competition.

Turkey's decision to open competition for the Altay comes at a time when some industry sources caution that the program faces several technical challenges, including an engine and transmission system for the tank.