Turkey's president appeared to rule himself out as a potential future prime minister on Friday, saying a "Putin-Medvedev model" under which he might swap roles with Prime Minister Tayyip Erdogan was not suitable for Turkey.

President Abdullah Gul's comments threw open the question of who might succeed Erdogan should he run for the presidency in an August election as expected. Gul had been seen as a potential future prime minister with Erdogan as head of state.

"I don't have any political plan for the future under today's conditions," Gul told reporters in the western province of Kutahya, when asked about the presidential election.

Russia's current Prime Minister Dmitry Medvedev replaced Vladimir Putin as president in 2008, while Putin became prime minister. They swapped roles in 2012.

Asked if a "Putin-Medvedev model" might be conceivable, Gul said such a formula would not be "appropriate" for a democracy.

Gul did not elaborate on what had led to his decision.

Erdogan told reporters after Friday prayers he had not heard Gul's words and would not comment before speaking with the president directly.

Gul co-founded the ruling Islamist-rooted AK Party with Erdogan and has remained a close ally. But he is viewed as a more conciliatory figure than the combative prime minister and their relations have at times appeared strained.

(Corrects fourth paragraph to reflect that Russia's Medvedev was First Deputy Prime Minister, not Prime Minister, before he became President in 2008.)