By Marcus George and Yeganeh Torbati
DUBAI, Aug 6 (Reuters) - Iran's incoming President Hassan Rouhani used his first press conference on Tuesday to offer an olive branch to the United States in protracted talks on Tehran's disputed nuclear programme, raising hopes of progress after years of stalemate.
Rouhani, seen in the West as a relatively moderate leader, said he was "seriously determined" to resolve the dispute and was ready to enter "serious and substantive" negotiations in order to do so.
Iran's critics say that it has used previous nuclear talks as a delaying tactic while continuing to develop nuclear weapons-related technology - something Tehran denies. Iran says it needs atomic power for energy and medical needs.
Rouhani said Iran would not abandon its nuclear programme, which it would uphold "on the basis of international law".
"We will not do away with the right of the nation," the 64-year-old said. "However, we are for negotiations and interaction. We are prepared, seriously and without wasting time, to enter negotiations which are serious and substantive with the other side."
"If the other party is also prepared like we are, then I am confident that the concerns of both sides will be removed through negotiations within a period which will not be very long."
Hopes for a diplomatic resolution to the nuclear issue have risen with Rouhani's victory over conservative rivals in June, when voters chose him to replace hardliner Mahmoud Ahmadinejad. A cleric whose watchword is "moderation", Rouhani is however still very much an Islamic Republic insider.
LAST TALKS DEADLOCKED
His words on Tuesday are likely to reinforce that view, although talks over Iran's nuclear programme have long had a habit of frustrating both sides.
The last high-level talks between Iran and world powers - the United States, Russia, China, Britain, France and Germany - were held in April and failed to break the deadlock.
Since Rouhani's victory at the polls, the United States has said it would be a "willing partner" if Iran was serious about finding a peaceful solution to the issue.
Adding to a sense of urgency and opportunity, Russia on Tuesday said fresh talks between Iran and world powers must not be delayed and should take place by mid-September.
Russian Foreign Minister Sergei Lavrov, speaking during a visit to Italy, said Russia "absolutely agreed" with Rouhani, and criticized moves to tighten sanctions against Iran, saying it was a time for dialogue, not ultimatums.
"Now it is critical to support the constructive approach of the Iranian leadership," he said in comments carried on Russian news agencies.
Russian leader Vladimir Putin is due to meet Rouhani for the first time as president in Kyrgyzstan in September.
In a letter to the new leader on Tuesday, the European Union said Rouhani had "a strong mandate to engage in dialogue" and added that it hoped for a new round of talks "as soon as practicable."
Both the United States and European Union have imposed sanctions on Iran amid suspicions of its nuclear intentions, and Washington and Israel have said all options, including military action, are open to stop Tehran from acquiring nuclear arms.
Rouhani criticised the embargoes, which have had a deepening impact on Iran's economy over the last year and a half as they slashed oil imports, the country's main source of income.
The measures have already cut Iran's oil exports by more than half compared to pre-sanctions levels of about 2.2 million barrels per day, helping to devalue Iran's currency and contributing to a steep rise in inflation.
"The goals of the sanctions in practice are piling pressure on various classes of the people," the president said.
"It is said (that) through sanctions they check Iran's nuclear activities. This is totally unfounded, and they themselves are cognizant of this fact ... It has nothing to do with the nuclear issue. It is pressuring people."