* Iranian will for final nuclear deal is strong - Rouhani
* Rouhani unbending in support for Syria's Assad
* President promises new attractive terms to energy chiefs
By Paul Taylor
DAVOS, Switzerland, Jan 23 (Reuters) - Iran is determined tonegotiate a comprehensive deal on its nuclear programme withmajor powers so it can develop its battered economy, PresidentHassan Rouhani said on Thursday, inviting Western companies toseize opportunities now.
Addressing the World Economic Forum in Davos, the pragmaticpresident said Tehran was negotiating with the United States aspart of a "constructive engagement" with the world and wantedWashington to back up its words with actions.
However, a day after a chaotic Syria peace conference fromwhich Iran was excluded, he was unbending in his support forSyrian President Bashar al-Assad. Ending "terrorism" backed bysome of Syria's neighbours was a precondition for any settlementof the country's civil war, he said.
Elected last year on a promise to improve Tehran's relationswith the outside world, Rouhani took the United Nations by stormin New York in September. His appearance in the Swiss resortlaunched phase two of a charm offensive aimed at endingsanctions that are crippling Iran's economy.
An interim deal with the United States, Russia, China,Britain, France and Germany - known as the P5+1 - came intoforce this week. This granted Iran a limited easing of thesanctions in return for temporary constraints on its uraniumenrichment and nuclear development.
Rouhani stressed his commitment to achieving a finalsettlement. "Iran has a serious will to come to an agreementwith the P5+1," he told the assembled business and politicalleaders. "I do not see a serious impediment in the way of thisagreement. The Iranian will is strong."
Asked what might prevent a long-term settlement, he citedthe risk of "pressure from other parties" - a veiled referenceto Israel, which denounced the interim deal as an "historicmistake" and urged the U.S. Congress to resist it.
Rouhani broke no new diplomatic ground in his speech. In aprivate session with energy executives, he promised a new,attractive investment model for oil contracts by September aspart of a drive to lure back Western business barred by theU.S.-led sanctions, participants said.
Relations with Europe were being normalised now that theinterim nuclear accord was being implemented, he said. Rouhanialso met European Commission President Jose Manuel Barroso onthe sidelines of the conference.
"Iran should use this window of opportunity withdetermination to move to a comprehensive long-term solution onthe nuclear issue," Barroso said in a statement. "This wouldopen up the potential for an improved relationship and broadercooperation."
At a separate meeting with U.S., European and Arabbusinessmen, Rouhani said Iran was seeking investmentparticularly in car manufacturing, oil and gas, petrochemicals,road and rail infrastructure and mining, a participant said.
He ignored a question from two U.S. businessmen who saidthey had Israeli passports and asked if they could invest inIran. The Islamic Republic does not recognise the Jewish state.
Most sanctions, including a severe squeeze on Iran's accessto the international financial system, remain in force and theUnited States has stressed Western companies should not regardIran as "open for business".
"PRUDENCE AND MODERATION"
Rouhani promised to pursue a consistent foreign policy of"prudence and moderation" to revive the economy.
He called for cooperation with all Iran's neighbours but didnot mention Gulf rival Saudi Arabia by name and refused, whenpressed twice, to include Israel among states with which Iransought friendly relations.
Israeli Prime Minister Benjamin Netanyahu, who was in Davosbut not in the hall during the speech, said afterwards thatRouhani's soft words bore no relation to reality, citing Iran'smilitary role in Syria and its support for the Palestinian Hamasmovement which seeks Israel's destruction.
"Rouhani continues Iran's deception show," Netanyahu said.
"The goal of the Iranian ayatollahs' regime, that hidesbehind Rouhani's smile, is to ease sanctions without giving uptheir programme to produce nuclear weapons," he said, urging theinternational community "not to be duped".
Rouhani repeated Iran's standard pledge not to seek nuclearweapons and said Tehran was willing to accept all safeguards andinspections of the U.N. nuclear agency, provided it was notsubjected to "discrimination". Western countries believe theatomic effort is aimed at developing a military capability.
"We never sought and will never seek nuclear weapons," thepresident said. "I declare that a nuclear weapon has no place inour security strategy."
But in a foretaste of tough negotiations on a long-termagreement, he said: "Iran will not accept any obstacles to itsscientific progress."
Some Western energy chiefs said they were impressed byRouhani's commitment to attract foreign investment in thesector, which has seen production cut by a third and exportshalved by the sanctions.
"The fact that the president of Iran came to the meetingtoday... is clearly a sign that Iran wants to open up tointernational oil companies," said Paolo Scaroni, chiefexecutive of Italy's Eni, who was at the meeting.
But he said Eni would stick strictly to the sanctions and return to Iran only when a permanent nuclear deal was concludedand contract terms were changed.
"It was an impressive presentation," said one of three otheroil executives who attended and spoke with Reuters on conditionof anonymity.
CONSTRUCTIVE ENGAGEMENT
The United States and other Western powers want Tehran toend high-grade uranium enrichment and shut down a heavy-waterreactor capable of producing plutonium nuclear fuel under anypermanent settlement. Iran rejects these steps.
With Saudi Prince Turki al-Faisal, a former intelligencechief and ambassador to the United States, sitting in theaudience, Rouhani said Iran sought cooperation "with thelittoral states of the Persian Gulf". However, he did not nameSaudi Arabia, which has expressed concern about the interimnuclear deal.
In a clear swipe at Riyadh and Qatar, he renewed criticismof countries he did not name which he said were supportingterrorism in Syria, saying this would rebound on them at home.
Senior Gulf Arab businessmen from Saudi Arabia and Bahrainwho heard the speech said it was hard to believe Rouhani wasgenuine about his wish for better relations with Iran'sneighbours. They also said any trade deals would be for cashonly until some payments channel could be arranged.
Iran was shut out of Wednesday's U.N.-sponsored Syrian peaceconference in Montreux, Switzerland, because of its refusal toendorse a framework for a transition from Assad's rule.
Rouhani later cancelled a planned news conference and leftthe building without taking any questions in public, except fromthe World Economic Forum's founder Klaus Schwab. Organiserscited "technical reasons", saying they could not provide anadequate room with simultaneous interpretation at short notice.