If the prosecutor decides to take the Democratic Society Party (DTP) to court at the conclusion of his probe, it could be banned.

The investigation was called after participants at the convention waved Kurdish flags and brandished posters of jailed Kurdish rebel leader Abdullah Ocalan.

Several shouted slogans in favour of Ocalan's Kurdistan Workers' Party (PKK), which has been waging a bloody battle for self-rule in Turkey's mainly Kurdish southeast since 1984.

"It is not possible for us to distance ourselves from the PKK. A peace strategy that excludes the PKK cannot be successful," media reports quoted Aysel Tugluk, the DTP's former co-chair, as saying at the gathering.

Representatives from Sinn Fein and Batasuna, the political wings of, respectively, the Irish Republican Army (IRA) and the Basque separatist movement ETA, as well as members of the European Parliament attended the convention.

It ended with Tugluk withdrawing from the party's leadership and leaving co-chair Ahmet Turk, a veteran Kurdish politician, alone at the helm, because Turkish legislation on political parties does not allow two leaders.

The DTP was set up in November with a pledge to try to resolve the long-standing Kurdish conflict in Turkey through peaceful means.

But it has so far failed to achieve any progress, with PKK violence mounting in the southeast.

The DTP has come under fire for sympathizing with the PKK, which is blacklisted as a terror group by Turkey, the European Union and the United States, and dozens of its members face prosecution for supporting the rebels.

The DTP advocates broader cultural and political rights for Kurds and campaigns for the abolition of a 10 percent electoral threshold required to enter parliament.

Kurdish politicians in Turkey are routinely regarded with suspicion and often seen as instruments of the PKK.