Prime Minister Ehud Olmert on Sunday said he would not let a new police investigation into his conduct prevent him from doing his job - his first public comments on an affair that has threatened to further weaken him politically as he tries to make peace with the Palestinians.

U.S. Secretary of State Condoleezza Rice's arrival in the region this weekend only highlighted concerns that Olmert might be too weak to shepherd through a peace deal that would require Israel to cede long-held land to the Palestinians.

The investigation is the fifth against Olmert since his government took office exactly two years ago and the latest in a longer string of probes to dog him during his three decades in politics. He has not been charged in the most recent corruption investigations, and has never been convicted of wrongdoing.

Still, the corruption probes have hurt his standing, which also has been battered by the inconclusive 2006 war in Lebanon, and ongoing Palestinian rocket and mortar fire at Israel from the Gaza Strip.

Speaking at the weekly cabinet meeting, Olmert said the latest investigation has unleashed a wave of rumors, most of them malicious and wicked.

"When the facts become clear," he said, "they will lay the rumors to rest," he insisted.

"In the meantime, I have an agenda as the prime minister of Israel," he said. "I intend to continue with this agenda and continue my job."

The affair touched off a media tempest, with newspaper front pages and radio stations focusing almost exclusively on Olmert's new predicament. Political opponents quickly predicted that Olmert's days at Israel's helm were numbered.

Against the backdrop of this latest investigation, the prime minister canceled traditional Independence Day interviews with Israel Radio, Army Radio and the news Website Ynet. His office confirmed the cancellations, citing the gag order on the investigation.

Meanwhile, Olmert's party Kadima elected to keep mum about the affair, despite confusion and embarrassment within the party, with none of the senior Kadima members rushing to respond to the vague charges.

According to sources in Kadima "this is a blow to the party, which only now has begun to recuperate in the polls and rehabilitate itself from the damages of the Winograd [2006 Second Lebanon War probe] report. This affair sounds dramatic, and is not confined to Olmert. We are all hurt by it. Either this is really serious, or [Attorney General Menachem] Mazuz will have a lot of explaining to do about how a prime minister was almost arrested on Friday."

The only member of Kadima to comment on the criminal investigation was MK Yoel Hasson who said that "from past experience, all the investigations against prime ministers began with a bang and ended up with nothing. The political arena must avoid hysteria and refrain from making hasty political decisions that could destabilize the government."

Associates of the prime minister said that precisely now, "when Olmert is finally on the right track and is promoting political processes, an investigation such as this is a painful blow."

Olmert was questioned on Friday in Jerusalem for a bit more than an hour. This was a relatively short interview meant mostly to hear his initial response to the suspicions against him and to secure his version of the story, to prevent him from diverting from it in the future.

At the end of the interview the Prime Minister's Bureau issued a statement to the press with Olmert's version about the suspicions against him, which was quickly followed by a Police announcement of the court's gag order.

According to sources close to the investigation, the evidence against the prime minister is "very serious."

"The initial evidence collected has been sufficiently sound, and there is a real basis for the suspicions against Olmert," a police source said.

Police said Saturday that they view this as the most serious case against the prime minister with the strongest evidence.

Thursday, Olmert's office issued a statement saying that the PM "is convinced that with the emergence of the truth as part of the police investigation, all suspicions against him will evaporate."

Police sources made it clear that one of the reasons for the rushed request to question Olmert stemmed from concerns that the investigation would be disrupted once critical information was revealed.

The same sources explained that the immediate interview stemmed from Olmert's status and the fact that the police could not impose restrictions, such as house arrest, preventing use of the telephone and meetings with persons with whom he could coordinate his version of events.

After the interview with the prime minister, members of the police investigation squad and officials from the Justice Ministry met with State Prosecutor Moshe Lador, and later, in a broader forum, with Attorney General Menachem Mazuz.

The two senior officials were briefed on the interview, and decisions were made on how to proceed with the investigation.

A Justice Ministry source close to the investigation said Saturday that the PM is not likely to be interviewed again in the coming days. The source described the evidence against Olmert as "not insignificant."

The Justice Ministry issued a statement Saturday night rejecting reports in which it was suggested that the ministry had taken a stance on the prime minister's continued stay in power, in light of the investigation.

Attorney Yehoshua Resnick, a former deputy state prosecutor, said Saturday that there is nothing wrong with urgent interviews, but acknowledged that he does not recall any instances in which a public figure was called in for questioning with the urgency that Olmert has been.

"In the past there have been quick interviews that were authorized by the State Prosecutor's Office," Resnick said. "For example, raids on a ministry where it was suspected material essential to an investigation was being destroyed. Such an urgent investigation is normally required to prevent coordination of testimonies with other suspects or the need to receive initial testimony from a suspect."

However, Resnick was highly critical of the decision to impose a gag order on the details of the case. At least, he said, it is necessary to reveal to the public at least the generalities of the investigation, so people will know what is going on.

"When it is an elected official, the public needs to know what suspicions are directed at him, especially when that person is the prime minister," Resnick said.