Iran said on Wednesday it was in touch with big powers to hold fresh talks soon but the European Union denied it, with Britain saying Tehran had yet to show willingness for negotiations on its disputed nuclear work without preconditions.
A year after the last talks collapsed, tensions are rising with the United States and EU preparing to embargo Iran's oil industry over its refusal to suspend a nuclear programme that the West suspects is meant to develop atom bombs.
Iranian politicians said US President Barack Obama had expressed readiness to negotiate in a letter to Tehran.
"Negotiations are going on about venue and date. We would like to have these negotiations," Iranian Foreign Minister Ali Akbar Salehi told reporters during a visit to Turkey. "Most probably, I am not sure yet, the venue will be Istanbul. The day is not yet settled, but it will be soon."
A spokesman for EU foreign policy chief Catherine Ashton, representing the six powers, denied there were any fresh discussions with the Islamic Republic to organise a meeting. "There are no negotiations under way on new talks," he said in Brussels. "We are still waiting for Iran to respond to the substantive proposals the High Representative (Ashton) made in her letter from October."
Britain was also dismissive. "There are no dates or concrete plans because Iran has yet to demonstrate clearly that it is willing to respond to Baroness Ashton's letter and negotiate without preconditions," a Foreign Office spokesman said.
"Until it does so, the international community will only increase pressure on it through further peaceful and legitimate sanctions," he said.
EU foreign ministers are expected to approve an embargo on Iranian oil at a meeting on Jan. 23, diplomats say.
"Ahead of (that meeting) Iran is chasing headlines and pretending that it is ready to engage," a Western diplomat said in reference to Salehi's remarks. "If it really is ready to sit down without preconditions the (six powers) would do so. Sadly, at the moment, it seems more interested in propaganda".
In reply to Tehran's threat to close the Gulf's vital oil shipping lane, the Strait of Hormuz, if sanctions prevent it selling oil, Obama has written to the senior cleric who sits atop the Islamic Republic's power structure, Iranian politicians said.
While Washington has yet to comment on the reported letter to Supreme Leader Ayatollah Ali Khamenei, several members of Iran's parliament who discussed the matter on Wednesday said it included the offer of talks.
"In this letter it was said that closing the Strait of Hormuz is our (U.S.) 'red line' and also asked for direct negotiations," the semi-official Fars news agency quoted lawmaker Ali Mottahari as saying.
"The first part of letter has a threatening stance and the second part has a stance of negotiation and friendship."
Ray Takeyh, senior fellow for Middle Eastern studies at the Council on Foreign Relations, said in a recent column in the Washington Post that there were doubts about Tehran's sincerity in wishing to return to talks.
"By threatening the disruption of global oil supplies, yet dangling the prospect of entering talks, Iran can press actors such as Russia and China to be more accommodating in an effort to avoid a crisis that they fear," Takeyh wrote. "Any concessions that Iran may make at the negotiating table are bound to be symbolic and reversible."