By Lin Noueihed

DUBAI, April 13 (Reuters) - Israeli Foreign Minister Tzipi Livni will visit Qatar for the first time on Sunday and hopes there is a chance to build a consensus among Arab nations against Iran's nuclear ambitions, which worry many Gulf states.

Livni's visit to speak at an international forum is the first by a senior Israeli official since President Shimon Peres visited Doha in January 2007, when he was deputy prime minister.

"Iran represents a threat to the region and to the world and we cannot tolerate a nuclear-armed Iran... I see an opportunity here," she said, speaking to Qatar's Al-Watan newspaper on the eve of her trip.

Like all six U.S.-allied Gulf Arab states, Qatar does not have official diplomatic ties with Israel but unlike them it does host a small Israeli trade mission.

Qatari officials, including Emir Sheikh Hamad bin Khalifa al-Thani, have met Livni before but her invitation to speak on Arab land remains a significant step amid icy Arab-Israeli ties.

Livni praised Qatar's willingness to talk to all parties in the Middle East conflict, and saw an opportunity for Israel and the Arabs to build a front against Iran's nuclear ambitions.

"Stopping Iran is in the joint interest of Israel and the Arab world together and generates the understanding that Israel and Islamic countries in the region face a common threat."

Like the other Sunni Muslim-ruled Gulf Arab countries, Qatar is concerned about the growing influence of Shi'ite Muslim Iran and its uranium enrichment programme.

Iran says its programme is meant for electricity generation, but Washington charges it wants to develop atomic weapons.

Livni is due to give a keynote speech on international dialogue and peace at the Doha Forum on Democracy, Development and Free Trade on Monday evening, according to the forum agenda.

Israeli officials said she was expected to meet with the emir and Prime Minister Sheikh Hamad bin Jassim al-Thani, but it was not clear if she will meet with other Arab leaders in Doha.

Livni dismissed rumours she was using the Doha conference to meet Palestinian or Syrian officials, but said she would meet with officials attending the three-day event.

Among the Arab officials set to attend the forum are the foreign minister of Oman, which closed a similar Israeli trade mission after the start of the Palestinian uprising in 2000.

Israel's Haaretz newspaper said Livni's speech was expected to "call on Arab nations to assist in the Israeli-Palestinian peace process by promoting a 'gradual' normalisation of ties".

Qatar, home to the world's third-largest natural gas reserves, hosts the U.S. military's Central Command, which oversees wars in Iraq and Afghanistan.

The country, which has grown from a backwater to host events from the World Trade Organisation talks to the Asian Games, is also home to Al Jazeera television network, which is critical of the United States and Israel.

Qatar has hosted some senior officials of the Palestinian Islamist group Hamas, which seized control of Gaza last year.

Livni is also widely expected to raise the fate of Israeli soldier Gilad Shalit, who was captured in a June 2006 cross-border raid from Gaza by Palestinian fighters. (Additional reporting by Avida Landau in Jerusalem; Editing by Matthew Jones)