Turkey's parliament reconvened on Wednesday for an emergency session to hear corruption allegations against four former government ministers.
The corruption scandal, which brought down the four ministers and prompted a cabinet reshuffle in December, has evolved into the most serious challenge yet to Prime Minister Recep Tayyip Erdogan's 11-year-rule.
The Turkish premier himself has also been implicated in the controversy with leaked audio tapes in which he can allegedly be heard talking to his son about hiding large sums of money.
Erdogan has accused followers of ally-turned-foe Fethullah Gulen, a US-based Muslim preacher, of concocting the graft probe to undermine his government ahead of crucial local polls on March 30.
The parliament returned from recess for the special session after the main opposition party requested it.
Erdogan is on the campaign trail and did not attend Wednesday's session.
His Justice and Development Party (AKP), which has won three elections in a row since 2002, plans to establish a parliamentary commission to investigate allegations involving the former ministers, media reported.
The ministers of interior, environment, and economy stepped down after the scandal erupted with police rounding up their sons on charges of bribery for construction projects and illicit money transfers to neighbouring Iran. Their sons were later released pending on trial.
Turkey's former EU Affairs Minister Egemen Bagis was replaced by Erdogan in a major cabinet reshuffle in the wake of the probe, after he was accused of being involved in the corruption scandal.