After being formally elected party leader, Kilicdaroglu said: "We will introduce a political ethics law. Racketeers, pillagers and swindlers have no place in parliament."

The CHP has struggled in offering itself as an alternative to the Islamic-oriented ruling Justice and Development Party (AKP), often appearing to be authoritarian and out of step with its social-democratic grass-roots.

Political scandal

The CHP suffered a blow earlier this month when a secretly taped video apppeared on the internet purportedly showing Deniz Baykal,its chairman, in an intimate encounter with a female legislator who used to be his aide.

Baykal stepped down soon after the sex scandal erupted.

Kilicdaroglu, a former head of Turkey's social security agency, led an association dedicated to fighting state corruption before winning a parliament seat in 2002.

He has since exposed documents alleging corruption that forced the resignation of two senior figures from the AKP.

The CHP is Turkey's oldest political party, having been founded by Mustafa Kemal Ataturk, the architect of modern Turkey, in 1923.

It lost the 2007 general elections to the AKP, which the CHP accuses of trying to undo the country's secular system by mixing Islam with politics.