A plan by right-wing legislators in Israel to commemorate the anniversary this month of the death of Meir Kahane, whose banned anti-Arab movement is classified as a terrorist organization, risks further damaging the prospects for talks between Israel and the Palestinians, US officials have warned.

A move to stage the commemoration in Israel's parliament, the Knesset, is being led by Michael Ben-Ari, who was elected this year and is the first self-declared former member of Kahane's party, Kach, to become a legislator since the movement was banned 15 years ago.

The US Embassy in Tel Aviv has sent a series of e-mails to Reuven Rivlin, the parliamentary speaker, asking that he intervene to block the event.

According to US officials, pressure is being exerted on behalf of George Mitchell, US President Barack Obama's special envoy to the region, who is concerned that it will add to his troubles as Israeli and Palestinian leaders clash over a possible move by the Palestinians to issue a unilateral declaration of statehood.

Some Israeli legislators have warned that Ben-Ari and his supporters are gaining a stronger foothold in parliament, in an indication of the country's increasing lurch to the right.

"Ben-Ari and the advisers he has brought with him are unabashed representatives for Kach and Kahane's ideas," said Ahmed Tibi, a Palestinian legislator and the Knesset's deputy speaker. "What we have is in effect a terrorist cell in the parliament."

Kahane, a US rabbi who emigrated to Israel in the early 1970s, advocated the expulsion of all Palestinians from "Greater Israel," an area that the far right believes encompasses not only Israel but also the occupied territories of the West Bank, Gaza Strip and East Jerusalem, and parts of neighboring states.

Kahane was elected to parliament in 1984 but was barred from standing again four years later. He was assassinated by an Egyptian-American in New York in November 1990.

In 1994, Kach was declared a terrorist organisation by Israel and the United States after Baruch Goldstein, an American-born supporter, went on an armed rampage through the Ibrahimi Mosque in the Palestinian city of Hebron, killing 29 worshippers and injuring 150.

Despite the ban, Kach is still active in many West Bank settlements, especially in and around Hebron, where shrines to Kahane and Goldstein regularly attract large numbers of devotees.

Ben-Ari, one of four members of the National Union elected to the 120-seat Knesset, has included as his parliamentary advisers two former Kach activists, Baruch Marzel and Itimar Ben Gvir, leaders of the far-right Jewish National Front. Mr Ben-Ari has never disavowed his support for Kahane, telling The Jerusalem Post this month that Kahane "dedicated his whole life to Israel - He was a great man and a great leader."

This month Ben-Ari was the voice on an advertisement on the Israeli radio station Reshet Bet to promote a public memorial service for Kahane held by his family. It was also reported that for the first time posters had been placed in many central areas of Jerusalem publicizing the event and declaring "We all know now - Meir Kahane was right."

The US has expressed more concern, however, at a commemoration being planned in parliament.

Michael Perlstein, the deputy secretary at the US Embassy, is reported to have e-mailed Rivlin several times, asking whether the commemoration was likely to be approved. According to e-mails leaked to the Israeli media, he added: "This is something Senator Mitchell and his team are following with some concern."

An embassy spokesman reiterated those concerns last week: "To stir up controversy at the same time that we are trying to get people back to the [negotiating] table, is not productive of that effort. It is only natural that Senator Mitchell would be paying attention to that - and the US government as well."

Rivlin has reassured the United States that he refused Ben-Ari permission to stage a commemoration but has also admitted that it would be difficult for him to stop a "stunt" by Kahane supporters in the chamber.

"We are talking about a provocation," Rivlin told the Haaretz newspaper. "The man [Kahane] and his outlawed movement cannot be separated. This is an attempt to bring the Kach movement into the Knesset through the back door."

Last week, Ben-Ari appealed against the speaker's decision to the House Committee, which rules on issues of parliamentary procedure. Rivlin has said he will abide by the committee's decision.

Its chairman, Yariv Levine of the ruling Likud Party, said he was not happy with Rivlin's refusal and is reported to be working with the speaker and Ben-Ari to find a solution.

Ben-Ari responded angrily to the US concerns: "I was elected to the Knesset by citizens of the independent state of Israel. The flagrant involvement of Mitchell has crossed a red line and it testifies to the bowed head of the Knesset speaker that is turning the Knesset into a dish rag."

Ben-Ari is probably not the only former member of Kach in the Knesset. Avigdor Lieberman, the foreign minister and leader of the far-right Yisrael Beitenu party, the third largest in parliament, is believed to have joined Kach when he first arrived in Israel in the 1970s. His membership was revealed in February by Yossi Dayan, the movement's former secretary general.

Last week Ben-Ari had to cancel a trip to the United States, his first overseas visit, after he was refused a US visa. He had intended to speak to American Jewish groups to encourage emigration to Israel.

To date, the only authorized parliamentary commemorations are for Yitzhak Rabin, the prime minister assassinated by a right-wing Israeli in 1995, and for Rehavam Ze'evi, a former general and leader of a far-right anti-Arab party, who was assassinated by Palestinian gunmen in 2001.