An Iranian MP suggested that parliament might advocate withdrawal from the nuclear Non-Proliferation Treaty (NPT) if Thursday's Geneva talks with major powers fail and "if the Zionists (Israel) and America continue their pressure on Iran" - a reference to policies including economic sanctions.

Washington has suggested possible new sanctions on banking and the oil and gas industry if Tehran fails to assuage Western fears it seeks nuclear weapons. U.S. officials believe sanctions could now have more effect, playing on leadership divisions evident since a disputed presidential poll.

Comments by Western and Iranian officials suggested little optimism ahead of the Thursday's rare meeting of the P5+1 - permanent U.N. Security Council members China, Britain, France, the United Sates and Russia, as well as Germany - with Iran.

"My expectation, or my hope, is that we will be able to get...the guarantees from Tehran, that the programme in which they are engaged in is a peaceful programme," EU foreign policy chief Javier Solana told reporters in Gothenburg, Sweden.

"I don't think it will be easy to ask for, but we will continue to engage."

Last week's news of a second uranium enrichment plant, under construction south of Tehran, added urgency to the Geneva talks. Uranium in less refined form can be used for power generation but in a more highly refined state is used in nuclear bombs.

Statements from Tehran on Tuesday allowed some ambiguity on Iran's readiness to talk.

"Iran will not discuss issues related to its nuclear "rights" ...in Geneva on Thursday," Ali Akbar Salehi, head of Iran's Atomic Energy Organisation, told reporters.

"But we can discuss about disarmament, we can discuss about non-proliferation and other general issues," he said. "The new site is part of our rights and there is no need to discuss."

Iranian state Press TV quoted Salehi as saying on Monday Tehran was in contact with the U.N. International Atomic Energy Agency (IAEA) over a date for inspection of the plant.

Iran's IRNA news agency quoted MP Mohammad Karamirad, a conservative and member of parliament's foreign policy and national security commission, as saying Iran could close the door completely to cooperation with world nuclear authorities.

"If the Zionists and America continue their pressure on Iran and if the talks...do not reach a conclusion, then parliament will take a clear and transparent position, such as Iran's withdrawal from the NPT," he said.

Iranian missile tests on Sunday and Monday added to tension with Western powers, who fear a hardline leadership in the Islamic Republic could ultimately use a threat of nuclear attack to pursue its political ends in the Middle East and beyond.

Interfax news agency quoted a senior Russian diplomat as saying missile test launches by Iran should not be used as an additional argument for imposing sanctions against Tehran.

Iran denies any plans for nuclear weapons and portrays international pressure on it over its programme as a Western plot, with deep historic roots, to isolate and destabilise the country.

ELECTION PROTESTS

Iranian lawmakers signed a statement expressing support for negotiations based on proposals put forward by Iran, which do not mention Tehran's own nuclear programme.

"We recommend the 5+1 to use this historic opportunity," the 239 MPs said in a statement quoted by state broadcaster IRIB.

"If the group of 5+1 repeats past mistakes instead of using this opportunity, the Iranian parliament would take other decisions as it did in the past."

In 2006, the Iranian parliament passed a bill obliging the government to review the level of its cooperation with the U.N. nuclear watchdog after the United Nations approved sanctions on Tehran over its atomic programme.

The Geneva meeting is the first such encounter since the June re-election of President Mahmoud Ahmadinejad stirred mass protests in Tehran and signs of division in the leadership over accusations of vote fixing. It is also the first since President Barack Obama took office, seeking to revive contacts.

Russia, though cautious on sanctions, has expressed concern about Iranian missile launches and about Tehran's nuclear programme. President Dmitry Medvedev has said "other means" could be employed if Geneva talks failed.