* EU's Ashton says to meet Iran Foreign Minister Zarif at UN
* Powers keen for talks after Iran elects moderate president
* Risk of war lingers amid Israeli hints of military action (Recasts with Ashton quotes, adds Zarif, Bildt comments)
By Justyna Pawlak and Adrian Croft
VILNIUS, Sept 6 (Reuters) - The European Union and Iran will discuss a resumption of nuclear negotiations during a United Nations gathering this month, possibly setting a date for a new round of talks aimed ultimately at preventing a new Middle East war.
Talks between Iran and six world powers overseen by the EU's top diplomat have been stalled since April. The West is keen to resume them with Iran having elected a moderate president but still expanding its uranium enrichment capacity and Israel brandishing hints of bombing runs on Iranian nuclear sites.
President Hassan Rouhani said on Thursday the Iranian foreign ministry would take over negotiations in what appeared a move to streamline Iran's nuclear diplomacy, after years of security hardliners dominating the process.
EU foreign policy chief Catherine Ashton spoke to Foreign Minister Mohammad Javad Zarif on Friday and agreed to meet him to discuss planning, including a date, for new talks on the sidelines of the annual U.N. General Assembly in New York.
"I was responding to the news that the foreign ministry will take responsibility of the talks," she told reporters about her call to Zarif, speaking ahead of a meeting of EU foreign ministers in Vilnius, Lithuania. "We have dates available and he and I will meet in order to get things moving."
Ashton said she has developed a "rapport" with Zarif since his appointment after Rouhani's election in June and had reiterated to him the six big powers' desire to talk soon.
Western powers in the group - the United States, France, Britain and Germany - believe Iran is seeking the ability to make nuclear weapons and have engineered painful international economic sanctions to pressure Tehran into making concessions.
The Islamic Republic denies any bomb agenda, saying it needs nuclear power for electricity generation and medical research.
The two non-Western big powers - Russia and China - are not convinced Iran seeks nuclear weapons capability but want it to clear up doubts about its intentions through a negotiated deal.
Some Western diplomats and analysts believe Rouhani, who has pledged a more conciliatory and transparent approach to foreign policy than under his hardline conservative predecessor Mahmoud Ahmadinejad, and his negotiators may be more open to compromise.
At the Vilnius meeting, Swedish Foreign Minister Carl Bildt said recent appointments by Rouhani, including the transfer of responsibility for nuclear talks to the foreign ministry from Iran's Supreme National Security Council, where conservative hardliners predominate, were signs "worth taking note of".
"They are all pointing in the same direction: that they (Iran) are more interested in dialogue with the international community," Bildt told reporters.
Rouhani's decision to put the foreign ministry in control of negotiations also smoothes relations between the two sides who have previously stumbled on agreeing the date and location of meetings. But the move could also backfire on him.
"Transferring the nuclear dossier to the Ministry of Foreign Affairs simultaneously increases the new nuclear negotiating team's tactical manoeuvrability and its strategic vulnerability," said Ali Vaez of the International Crisis Group.
"Rouhani and Zarif can move with more agility but blame for any potential failure will be put squarely on their shoulders."
Zarif told Iran's Mehr news agency on Friday concessions from the West were vital to progress in nuclear diplomacy.
"In the conversation with Mrs Ashton I emphasised that if the political will is there and the necessary preparation to resolve the issue in a form that protects Iran's rights is apparent, then we are ready to take steps," he said.
Iran has repeatedly said the international community should recognise its "right" to refine uranium for peaceful purposes, but the six powers say Tehran should accept stringent oversight by International Atomic Energy Agency inspectors.
Iran also wants sanctions, above all those hitting its banks and oil industries, lifted before any concessions on enrichment.
A European court dealt another blow to efforts to inflict economic pain on Iran on Friday, ruling the EU has failed to sufficiently justify sanctions against seven Iranian firms, two of which were seen by Washington as arms buyers.
European courts have ruled against sanctions in a number of cases over the last year on grounds of lack of evidence linking targeted companies to Iran's nuclear programme, causing alarm in some European capitals and in Washington. (Additional reporting by Yeganeh Torbati and Marcus George in Dubai; Editing by Mark Heinrich)