TEHRAN/VIENNA/MOSCOW: Iran’s showdown with the West slid closer to dangerous confrontation Tuesday as international alarm over a new uranium enrichment plant raised the stakes. Both sides were digging in, with Iran’s defiance hardening and the United States and European Union actively taking steps to fracture the Iranian economy through further sanctions. China, which rejects the sanctions, warned of disastrous consequences if the Iranian nuclear row escalated into conflict, while Japan said it was “very concerned.”

The U.N. atomic agency’s confirmation Monday that Iran had begun enriching uranium in a new, underground bunker southwest of Tehran was seized upon by the U.S., Britain, France and Germany as an unacceptable “violation” of U.N. Security Council resolutions.

Russia, which has relatively close ties with Iran, also voiced concern over the new plant.

“Moscow has with regret and worry received the news of the start of work on enriching uranium at the Iranian plant,” a Foreign Ministry official was quoted as saying by the ITAR-TASS news agency.

“We should recognize that Iran is continuing to ignore the demands of the international community [and] that it [should] respond to their concerns regarding its nuclear program,” the official was quoted as saying.

Iran’s envoy to the International Atomic Energy Agency, Ali Asghar Soltanieh, tagged the West’s stance as “politically motivated.”

The underground Fordow plant had been revealed two years ago and documented, he said. The 20-percent enriched uranium it was to produce would be used for “peaceful and humanitarian” purposes, namely isotopes for cancer treatment, he said.

An official at the IAEA, the U.N. nuclear watchdog, said inspectors were expected to visit Iran “soon” to discuss their worries about possible military aspects to its nuclear program.

Both Soltanieh and the IAEA stressed the U.N. nuclear watchdog had 24-hour cameras there and inspectors to keep it under watch.

That seemed unlikely to reassure the United States, though, or its chief Middle East ally, Israel, analysts said.

“Israel, which has already warned Iran that it could take military action against installations, is very, very worried by this facility ... We are moving into dangerous territory,” said Mark Hibbs of the Carnegie Endowment for International Peace.

But while Iran downplayed the significance of Fordow – and affirmed it was ready to resume nuclear talks with world powers that collapsed a year ago – it continues to send tough signals to states contemplating further sanctions.

Its elite Revolutionary Guards have said they are about to launch new navy maneuvers in the Strait of Hormuz, at the entrance of the Gulf, a move aimed at showing the Islamic Republic can close the waterway if its oil exports are blocked or severely curtailed.

China, which buys 20-22 percent of Iran’s crude oil, warned against conflict. “We urge all relevant nations to ... refrain from taking actions that will intensify the situation and make common efforts to prevent war,” Chen Xiaodong, a top Chinese diplomat on Middle East affairs said in an online interview with his country’s state press. “Once war starts in this region not only will the relevant nations be affected and attacked, it would also ... bring disaster to a world economy deep in crisis,” he said.

The United States has said closing the strait would be a “red line” and it would continue deploying its warships to the Gulf.

Oil prices stayed high on the threats and counterthreats, amid buoyant U.S. consumer data. West Texas Intermediate crude was over $102 a barrel while Brent North Sea crude was over $113.

The European Union, meanwhile, is poised to declare a ban on Iranian oil imports. An EU foreign ministers’ meeting on the issue scheduled for the end of this month has been brought forward a week, to Jan. 23, an EU official in Brussels told AFP.

France’s Foreign Minister Alain Juppe said other major oil exporters would increase their production in order to steady world markets if the embargo is imposed. “We have made discreet contacts in this direction. The producers don’t want to talk about it, but they are standing ready,” Juppe said.

U.S. President Barack Obama signed into law on New Year’s Eve sanctions against Iran’s central bank due to come into effect within months.

His Treasury Secretary Timothy Geithner was in Beijing Tuesday in an effort to get China to drop its steadfast opposition to new sanctions on Iran and to come on board, at least to some extent.

Japan’s foreign minister, on a Gulf tour to seek assurances over oil supplies, also raised the alarm and called for a diplomatic solution. His country buys about 14 percent of Iran’s crude.

“Japan is very concerned about the latest developments,” Koichiro Gemba said. “We believe that we should solve the problem diplomatically and peacefully. That is why dialogue with Iran should continue.”

Japan asked Saudi Arabia and the United Arab Emirates to supply it with more oil, Japanese Foreign Minister Koichiro Gemba said Tuesday, if tighter Western sanctions threaten to reduce its oil imports from Iran.

Foreign Minister Gemba, who has been on a visit to Turkey and Gulf Arab countries since last week in what some analysts said could be a sign that Tokyo is seeking assurances from Gulf producers that they would compensate for any potential loss of Iranian oil.

“We want an increase in the quantity of oil that Japan needs [from these countries],” Gemba, speaking through an interpreter, said at a joint news conference in Abu Dhabi with UAE Foreign Minister Sheikh Abdullah bin Zayed al-Nahayan.

Japanese Foreign Ministry spokesman Masaru Sato declined to discuss the quantities of extra oil sought by Japan but said a team of technical experts was to travel to Saudi Arabia and the UAE to discuss the details.