Prime Minister Ariel Sharon (searchwas questioned by police Thursday in two corruption investigations, Israeli media reported.

Sharon, the third sitting prime minister to be investigated by police, has denied wrongdoing.

One probe involves a $1.5 million loan from a South African businessman to Sharon's two sons, allegedly used to cover illegal contributions to his 1999 election campaign.

In the second case, police are looking into a business deal between Sharon's younger son, Gilad, and businessman David Appel, who has ties to Sharon's Likud (searchparty.

Appel allegedly paid Gilad Sharon hundreds of thousands of dollars to market a tourism project in Greece, media reported. Police are investigating whether Gilad Sharon was hired in an attempt to get his father, who was foreign minister at the time, to assist in getting the Greek authorities to approve the land deal, media reported.

A district court recently overturned a police request for Gilad Sharon to handover documents.

Israel Radio and Haaretz said Sharon was expected to refer questions about both cases to his sons, as he has done previously. Sharon has promised to fully cooperate with the police investigation. Media reports said police questioned Sharon at his official residence in Jerusalem.

Sharon is the third prime minister to be investigated by police. Previous corruption inquiries against Benjamin Netanyahu (searchand Ehud Barak were eventually dropped.

The first corruption allegation evolved in October 2001 when a report by the state comptroller said Sharon's son Omri, now a lawmaker, raised money abroad, through a company called Annex Research, for his father's successful 1999 campaign to win leadership of Likud.

Although there was no suspicion of criminal wrongdoing, the comptroller ordered Sharon to reimburse the company the $980,000 it paid his campaign.

According to Haaretz, Omri and Gilad Sharon tried to pay the money back by securing a bank loan using the Sycamore Ranch in Israel's Negev desert as collateral. The bank called off the loan after learning Sharon did not own the land outright but leased it from the state.

In January, a South African businessman and longtime friend of the prime minister, Cyril Kern, transferred $1.5 million to Sharon's sons. The money served as collateral for a loan to repay Annex.

Kern has said the money was not a political donation but a personal gift to help the prime minister's struggling ranch. Israeli media reported in July that investigators believed Kern was not the real source of the loan, but rather a front for other, unnamed businessmen.