Rice made her remarks after talks with British Prime Minister Tony Blair and Foreign Secretary Jack Straw at the start of a week-long tour of Europe and the Middle East.

The Europeans have expressed fears that hardening US rhetoric against Iran could herald a preemptive assault to knock out Iran's suspected nuclear weapons program.

"The question is simply not on the agenda at this point," the chief US diplomat said at a news conference with Straw.

"We have diplomatic means to do this," Rice said.

"We have many diplomatic tools still at our disposal and we intend to pursue them fully."

Britain and its EU partners Germany and France have been engaged in halting efforts to persuade the Islamic republic to renounce any nuclear ambitions, with some European officials complaining the United States has not been sufficiently involved.

A senior state department official, who asked not be named, said that Iran was one of the topics discussed by Blair and Rice during a 90-minute breakfast meeting that also include 15 minutes head-to-head without aides.

Although Rice side-stepped a direct question on whether the United States supported regime change in Tehran, the official signalled a more aggressive US tone in support of Iranians fighting to change the hardline Islamic regime and bring democratic reform.

"The president and the secretary have made it more explicit that we support the aspirations of the Iranian people to control their own government," he said.

Straw sought to project a united front on the issue.

He said the efforts of the three European Union countries, to the extent that they have been successful, have "only worked because we have been backed by an international consensus.

"Absolutely fundamental to the international consensus has been the support we have received in the IAEA (Vienna-based International Atomic Energy Agency) board and in many other ways from the United States, he said.

"It's been a joint diplomatic effort, albeit three countries are directly involved in the negotiations."

The senior US official insisted however that the Europeans had not asked for direct intervention by Washington in the discussions.

Rice also insisted the world community was united in its drive to contain the nuclear threat from Iran. "It is the Iranians who are isolated on this issue, not the United States," she said.

Washington has ratcheted up its rhetoric against Iran in recent days, with Rice telling reporters en route to Europe Thursday that Tehran's human rights record was "something to be loathed".

Straw rejected suggestions that such strong language could compromise efforts to negotiate with Iran, and basically endorsed Rice's comments.

"I would be astonished if Secretary Rice had not had strong feelings about the human rights record of the Iranian regime because that is shared by us," Britain's top diplomat said.

He said that, while there had been some improvements in Tehran under Iranian reformers, "that has now gone backwards and therefore is a matter of profound concern."

Rice also warned Iran against meddling in neighboring states Afghanistan and Iraq, where the United States has launched military operations as part of its "war against terrorism" since the September 11, 2001 attacks.

"There's nothing wrong with relations between Iran and its neighbors, that would be only natural but that efforts to undermine democratic developments in these countries would be wrong," Rice said.

On another subject, Straw sought to mollify the United States which has expressed strong opposition to plans by the European Union to lift a 15-year-old arms embargo on China.

The Europeans say the weapons ban slapped on China after the 1989 massacre of pro-democracy students is outdated, but Washington insists a lifting of the embargo would send a wrong message on human rights and have serious military implications.

"We want to ensure (along with EU partners) that the justifiable anxieties of the United States are factored into any decisions that we take," Straw said.

Straw also appeared to seek accommodation with the Americans on the venue for prosecution of suspected war criminals in Sudan's western region of Darfur, where some 70,000 people have died in fighting between rebels and Khartoum-backed forces, or in mass killings of civilians.

The United Nations has suggested using the International Criminal Court based in The Hague but Washington is pressing to create a special UN tribunal in Arusha, Tanzania, where a court already exists to try crimes against humanity stemming from the 1994 Rwanda genocide.

"All of us know that the natural authority of the international community is greatly strengthened where there is a consensus behind a Security Council decision, and that's what we shall be working to achieve," he said.

Rice arrived later in Germany for talks with Chancellor Gerhard Schroeder on the second leg of her trip which will also take her to Poland, Turkey, Israel, the West Bank, Italy, France, Belgium and Luxembourg.

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