Mrs Clinton was responding to accusations by Suha Arafat that Israel had contaminated Palestinian areas with poison gas.

"Everyone who supports this (peace) effort should refrain from inflammatory rhetoric and from baseless accusations... that could in any way adversely affect what the parties are attempting to achieve," the US First Lady said at a press conference in Jordan.

"We do not believe that any kind of public inflammatory statements or excessive rhetoric is helpful to the peace process."

Suha Arafat: rebuked for cancer claim

On Thursday, Mrs Clinton had listened politely in the West Bank city of Ramallah as Suha Arafat unleashed a torrent of accusations against Israel.

"It is important to point out here the severe damage caused by the intensive daily use of poison gas by Israeli forces in the past years that has led to an increase in cancer cases against Palestinian women and children," Mrs Arafat said.

She added that 80% of water resources were contaminated, and that the ground was full of chemicals banned internationally.

New York politics

Mrs Clinton had come under attack from the camp of a potential political opponent, New York mayor Rudolph Giuliani, for failing to denounce Mrs Arafat's remarks quickly enough.

"It's inconceivable that there would be no comment from Mrs Clinton in the face of these abhorrent and ridiculous accusations," said the director of Mr Giuliani's political action committee, Bruce Teitelbaum.

The First Lady views a mosaic in Petra

Mr Giuliani and Mrs Clinton are expected to be rivals in an election next year for the US Senate seat from New York, although Mrs Clinton has not yet declared her candidacy.

At the press conference in Jordan during a visit to the 2,000-year-old city of Petra, she said the full English translation of Mrs Arafat's comments had only been made clear to her later.

The chief Palestinian negotiator, Saeb Erekat, said Mrs Arafat had not intended to cause Mrs Clinton any embarrassment.

The Israeli Government rejected Mrs Arafat's claims, saying that they poisoned the political atmosphere.

The Israeli army has always insisted that it uses conventional tear gas when operating in Palestinian areas.

Officials sent a sharp protest to an anti-incitement commission established as part of the peace process. It includes an American member, and meets in a few days time.

The Jewish vote

Mrs Clinton's four-day visit to Israel, Jordan and the areas under Palestinian control is in her official capacity as the US First Lady.

However, it may boost her standing with New York's large Jewish population.

On this trip, she has refused to discuss either her previously stated support for a Palestinian state, or her endorsement in July of a Jerusalem under permanent Israeli sovereignty.

At her press conference she said that such sensitive questions should be left to the negotiators.