Iran said on Wednesday that "no nuclear activity whatsoever" has taken place at its military site of Parchin, which UN nuclear watchdog inspectors demanded last week to visit but were refused.

"No nuclear activity whatsoever has taken place on the Parchin site," the head of Iran's Nuclear Energy Organisation, Fereydoon Abbasi Davani, was quoted by the official IRNA news agency as saying after a cabinet session.

"It is up to the country's military officials to decide any request by foreign nationals to visit Parchin," he added.

The International Atomic Energy Agency said last week it "continues to have serious concerns regarding possible military dimensions to Iran's nuclear programme" following an unsuccessful visit to Tehran by a five-strong inspection team.

The inspectors, who visited February 20-21, had asked to see the Parchin military base east of Tehran but Iranian officials rejected the request.

An IAEA report published in November said there was a "a large explosives containment vessel" at Parchin being used to test big amounts of conventional explosives consistent with designing a nuclear warhead for Iran's Shahab-3 ballistic missiles.

As a signatory to the Nuclear non-Proliferation Treaty (NPT) supervised by the IAEA, Iran has to submit to UN inspections at its declared nuclear sites.

But military sites that do not have confirmed nuclear activities are off-limits unless provided for by agreement or under the terms of an Additional Protocol to the NPT that Iran briefly adhered to but dropped in 2006.

Abbasi Davani was quoted as saying: "There is no reason for us to give access to any geographical point in our country at the mere request of the (UN) agency."

The Iranian nuclear chief said he hoped that talks with the IAEA "will continue in the future."

But he said that, while "we have no problem to further explain our nuclear activities" to the IAEA, "we need to consider our rights and national interests."

He notably dismissed imposing any "set timeframe" on Iran for it to answer IAEA questions.

The IAEA says that, following its failed talks in Tehran last week, it has no plans for future talks with Iranian officials.

It said last Friday that "major differences" exist with Iran.

Western members of the IAEA fear that Iran has long been hiding a nuclear weapons programme behind its atomic energy activities, and that it is getting close to the scientific threshhold of being able to make an atomic bomb.

Tehran denies that it is pursuing nuclear weapons.

Israel, which is not part of the NPT and which has the Middle East's sole though undeclared nuclear arsenal, has threatened to attack Iranian atomic facilities.

Netanyahu takes Iran nuclear fears to Washington
Jerusalem (AFP) Feb 29, 2012 - Israeli premier Benjamin Netanyahu will carry his warnings on the dangers of a nuclear Iran to the White House next week for talks amid renewed speculation over an Israeli attack on the Islamic Republic.

Netanyahu has already made clear that Iran's nuclear programme, which Israel fears masks a weapons drive, will top his agenda in Washington.

"There is no doubt that one issue will be at the centre of our talks, and that is, of course, the continued strengthening of Iran and its nuclear programme," he told his cabinet on Sunday.

Experts in Israel say Netanyahu's discussions with President Barack Obama will be a chance for the allies to sound each other out on their sometimes divergent positions on Tehran's nuclear programme.

"The prime minister wants to make Iran the central subject and I think the president this time does as well," Israeli political scientist Jonathan Rynhold told AFP.

"There is a major disagreement between the (US) administration and the Israeli government about where the red line is on the Iranian nuclear programme," said Rynhold, of Bar Ilan University, near Tel Aviv. "That will be a major issue of tension."

Netanyahu and Obama are to meet on Monday and the Israeli premier will address a convention of the American Israel Public Affairs Committee lobby group that evening.

It will be his first visit to the United States since September, when he met the president on the fringes of the UN General Assembly.

Obama is to speak to AIPAC on Sunday, when Netanyahu arrives in Washington, after a weekend stopover in Canada, where he will meet Prime Minister Stephen Harper, a keen backer of Israel.

"It's basically a courtesy call and a thank you call in terms of Canada's outspoken support for Israel," Zachariah Kay, a scholar at Jerusalem's Hebrew University and founder member of the Israel Association for Canadian Studies, said of the Ottawa visit. "Keeping friends intact is the important point."

Some of its other friends have been piling pressure on Israel to desist from attacking Iran and allow time for a regime of international sanctions to kick in.

US military chief Martin Dempsey, in an interview with CNN earlier this month, warned that it would be "premature" to launch military action against Iran.

"Israel will be under a lot of pressure to give these sanctions time to work," Rynhold said, adding that the United States could offer its own guarantees to the Jewish state.

"I think that if the administration were to give the Israeli government the impression that they would actually use force to prevent Iran going nuclear then that would definitely serve to tip the balance in the Israeli government in terms of waiting considerably longer."

"I think that in any event Israel's unlikely to do anything in the next three months because President Obama will make a very strong case that sanctions have to be given time and I think that argument is likely to win, at least in the short term."

Iran has topped the agenda in US-Israel talks of recent weeks, which have included visits here by US National Security Adviser Tom Donilon and US intelligence chief James Clapper.

Israeli Defence Minister Ehud Barak left for Washington on Monday on a two-day US trip expected to include meetings with Vice President Joe Biden, Defence Secretary Leon Panetta, and Donilon.

The United States is not alone in wanting to rein in Israel, the sole if undeclared nuclear power in the Middle East.

British Foreign Secretary William Hague has said it would not be "wise" for Israel to take military action against Iran, echoing comments earlier this month by French President Nicolas Sarkozy.

In 1981, Israel launched a pre-emptive strike on the unfinished Osirak reactor outside Baghdad, leaving US officials stunned and earning it a sharp rebuke from its American ally.

For now, Israel says it is keeping all options open for dealing with Iran's nuclear programme, which much of the international community fears masks a weapons drive, despite Tehran's denials.

"The state of Israel is a sovereign state; it has the right and capacity to defend (itself) against any threat," President Shimon Peres said last week. "When we say that all options are on the table, we really mean it."