JERUSALEM, August 8, 2008 (AFP) - Israeli police questioned Prime Minister Ehud Olmert on Friday for the second time since he announced he would resign after his centrist Kadima party chooses a new leader in September.

Anti-fraud officers were at Olmert's official residence in Jerusalem to conduct the interview, the fifth since claims the premier accepted illegal funds from a wealthy US financier emerged in May.

Dogged by six police investigations over alleged wrongdoing in the years before he took office in 2006, Olmert, 62, annnounced last week he would step down after Kadima party holds a leadership election on September 17.

Public radio said Friday's questioning would likely focus on the graft allegations as well as claims of influence peddling.

On Thursday, police questioned a former aide to Olmert over the influence peddling allegations that date back to the time when Olmert was trade and industry minister between 2003 and 2006.

The advisor, Eldad Rothman, was placed under 24-hour house arrest. The Maariv newspaper cited law enforcement sources as saying the measure was necessary in order to prevent obstruction of the investigation against Olmert.

On August 1, police had questioned Olmert on claims he sent out multiple bills for the same overseas trips and asked him about suspicious transfers of cash.

The allegations against Olmert, which all date back to the time before he took office in 2006, had prompted widespread calls for his resignation, which even several of his allies supported.

In his dramatic resignation announcement on July 30, Olmert admitted he made 'mistakes' during his time in office but that he would fight to prove his innocence.

Foreign Minister Tzipi Livni and hawkish Transport Minister Shaul Mofaz are seen as the frontrunners in the race to become leader of Kadima, the party founded by Olmert's predecessor and mentor Ariel Sharon.

But political analysts believe it is unlikely that whoever wins the Kadima leadership would be able to garner enough support to form a new coalition government.

This means Olmert, also a former mayor of Jerusalem, may remain at the head of a caretaker government for months until a general election is held.

Opinion polls indicate right-wing Likud leader and former prime minister Benjamin Netanyahu is the favorite to take over from Olmert as prime minister.

Unless early elections are held, Israelis are not scheduled to go to the polls until 2010.

Olmert's decision to go also has cast a shadow over already slow-moving US-backed peace negotiations with the Palestinians and recently revived indirect talks with Syria.

He held talks with Palestinian president Mahmud Abbas on Wednesday in their latest meeting aimed at trying to reach a peace deal by the end of this year, with Israel pledging to release Palestinian prisoners in a goodwill gesture.