Police have been investigating illegal political contributions allegedly made in 1999, when Mr Sharon was running for the leadership of the Likud Party.

Last November Mr Sharon's son Omri pleaded guilty to violating party funding laws.

However, the prime minister has always denied any involvement.

Lior Chorev, a key Sharon aide, dismissed the report.

"No official is saying this, a reporter is saying this," he said. "Since when do I need to respond to speculation of a reporter on Channel 10."

Computer files

The channel showed what it said was a police document that had been presented to a Tel Aviv district court, outlining evidence of the alleged bribe.

A police spokesman told the AFP news agency the evidence came from a computer confiscated in a raid on a house in Israel belonging to the family of an Austrian financier, Martin Shlaff.

"We suspect that there could be proof within Shlaff's computer data that the sum of $3m was transferred to the Sharon family," the spokesman, Mickey Rosenfeld, said.

However, police had been prevented from examining the computer hardware by a temporary court order obtained by Mr Shlaff's lawyers, he said.

The news followed Omri Sharon's resignation from parliament on Tuesday.

He is due to be sentenced later this month for providing false testimony and falsifying documents, and violating funding laws during his father's election campaign.

Prosecutors are demanding he go to prison.