Well-wishers hailed Iran's nuclear negotiators as they returned to Tehran yesterday from reaching a potentially historic framework deal with world powers, but Israel warned it was a "very dangerous" step.

Prime Minister Benjamin Netanyahu demanded that any nuclear agreement signed with Iran must endorse Israel's right to exist, while also insisting pressure be kept

up to ensure a sound deal is reached.

While calling the emerging deal a bad one, he said the choice was not only between abaddealor war.

"There is a third alternative - standing firm, increasing the pressure on Iran until a good deal is achieved, " he said in a statement.

And" Israel demands that any final agreement with Iran will include a clear and unambiguous Iranian recognition of Israel's right to exist."

His comments followed a special session of his powerful security cabinet in the wake of Thursday's framework agreement between the Islamic republic and world powers, hammered out at marathon talks in Switzerland.

"The cabinet is united in strongly opposing the proposed deal," he said.

"This deal would pose a grave danger to the region and to the world and would threaten the very survival of the state of Israel."

"The deal would lift sanctions almost immediately and this at the very time that Iran is stepping up its aggression and terror in the region and beyond the region."

“Such a deal paves Iran's path to the bomb," he added.

"And it might very well spark a nuclear arms race throughout the Middle East and it would greatly increase the risks of terrible war."

Israel is the Middle East's sole, albeit unacknowledged, nuclear power. It has been the loudest opponent of reaching a deal that would leave Iran with atomic capabilities.

Shortly after the outline of the deal was revealed, Israeli officials criticised it as "a historic mistake which will make the world far more dangerous".

Iran and six world powers agreed the outlines of the deal aimed at curbing Tehran's nuclear drive on Thursday - in a major breakthrough in the 12-year standoff between Iran and the West.

US President Barack Obama welcomed the "historic understanding" with the Islamic republic after decades of hostility, warning like other leaders that work remains to finalise a highly complex agreement by June 30.

In Iran - where crippling sanctions over its nuclear ambitions have left many suffering - the mood was joyful.

Hundreds of Iranians took to the streets of Tehran in celebration after the agreement was announced, with drivers sounding their horns in approval along the capital's longeststreet, Val-e-AsrAvenue.

Arriving in Tehran from the negotiations in the Swiss city of Lausanne, Foreign Minister Mohammad Javad Zarif and his team were welcomed by dozens of well-wishers.

"Viva Zarif! Viva Araghchi!" the crowd chanted, in reference to the minister and top negotiator Abbas Araghchi.

In remarks at the airport, Zarif praised supreme leader Ayatollah Ali Khamenei for "his remarkable support for the negotiating team and his guid-

ance" in the talks, the official IRNA news agency reported.

Reaching out to Iranian hardliners who have opposed any deal that would curb Tehran's nuclear activities, Zarif said the agreement was not finalised.

"This set of solutions will be the basis for writing a final document," he said.

"We are proud because we will never surrender... but in return for the advantages that we gain, we will give things in return so we can move on," he said. 'HISTORIC MISTAKE'

Residents lined the streets as Zarif drove away from the airport, many carrying Iranian flags, with the minister emerging from the sunroof of his car and waving to the crowd.

Khamenei will have the final word on the agreement, under which Iran agreed to sharply curtail its nuclear programme in return for the lifting of sanctions.

Iran's arch-foe Israel, widely assumed to have atomic weapons of its own, slammed the outline agreement as a "historic mistake" and said it would threaten the survival of the Jewish state.

"This framework is a step in a very, very dangerous direction," government spokesman Mark Regev told journalists, adding that Iran's "single goal" was to build a nuclear bomb.

Iranian President Hassan Rouhani said the drafting of a full accord was to begin immediately after Thursday's announcement. He was to make a statement later to reporters in Tehran.

Under the outline deal, the United States and the European Union are to lift all nuclear-related sanctions on Iran once the UN atomic agency has verified that Tehran has stuck to its terms.

All past UN nuclear resolutions on Iran would also be lifted.

The so-called P5+1 group - the United States, Britain, China, France and Russia plus Germany - hope that the deal will make it virtually impossible for Iran to make nuclear weapons.

Successful implementation of the deal could put Iran and the United States on the road to better relations after 35 years of animosity since the 1979-1981 hostage crisis in Tehran.

But Obama needs a deal which he can sell to hostile Republicans in Congress, who remain suspicious of Iran's pledges and are threatening to push for new sanctions from April 14.

And analysts were warning that the agreement was far from done.

"This accomplishment is not final. It is as fragile as the forces against it are formidable," Ali Vaez from the International Crisis Group told AFP.