The investigation follows a complaint by police in the eastern city of Igdir where Leyla Zana spoke at a rally Friday in support of dozens of Kurdish independent candidates running in Sunday's legislative elections.

"It is time to divide Turkey into states," newspapers quoted her as telling the crowd. "Ankara: Divide the country into states and establish the state of Kurdistan."

Mustafa Kucuk, the chief prosecutor of Igdir, said in a written statement carried by Anatolia news agency that the investigation would determine whether Zana violated laws on incitement and state unity.

Zana has already served a 10-year sentence for collaborating with separatist Kurdish rebels fighting the Ankara government.

In a television interview Saturday, Prime Minister Recep Tayyip Erdogan harshly criticized Zana's remarks and called for an investigation.

"These are very unfortunate remarks," he told the Kanal 7 network. "No one can... make such a provocation on the eve of the elections."

Turkey's unitary status is a highly charged issue amid mounting violence by the outlawed Kurdistan Workers' Party (PKK), which has been fighting a bloody campaign since 1984 for self-rule in the country's mainly Kurdish southeast.

Many oppose moves to clip the powers of the central government out of fear that it could lead to a break-up of the country.