PARIS/MOSCOW: A new East-West front opened Wednesday over an atomic agency report on Iran with Western leaders calling for expanded sanctions against Iran, and veto-wielder Russia indicating it would block any new measures at the U.N. Security Council.

The U.N. watchdog report, released late Tuesday, released a trove of intelligence suggesting that Iran is seeking nuclear weapons.

France said it would summon the Security Council. Britain said the standoff was entering a more dangerous phase and the risk of conflict would increase if Iran does not negotiate.

The Security Council has already imposed four rounds of sanctions on Tehran since 2006 over its nuclear program, which Western countries suspect is being used to develop weapons but Iran says is purely peaceful.

There has been concern that if world powers cannot close ranks on isolating Iran to nudge it into serious talks, then Israel -- which feels endangered by Tehran’s nuclear program -- will attack it, precipitating a Middle East conflict.

“Convening of the U.N. Security Council is called for,” French Foreign Minister Alain Juppe told RFI radio. Pressure must be intensified, he said, after years of Iranian defiance of U.N. resolutions demanding it halt uranium enrichment, which can yield nuclear fuel for power stations or weapons.

“If Iran refuses to conform to the demands of the international community and refuses any serious cooperation, we stand ready to adopt … sanctions on an unprecedented scale,” Juppe said.

But Moscow made its opposition to new sanctions clear.

“Any additional sanctions against Iran will be seen in the international community as an instrument for regime change in Iran. That approach is unacceptable to us,” Deputy Foreign Minister Gennady Gatilov told the Interfax news agency.

Russia, which has significant trade ties with Iran, has called for a phased process under which existing sanctions would be eased in return for actions by Tehran to dispel international concerns.

But in talks between Iran and big powers that would be needed to achieve that goal, the sides have been unable to agree even on an agenda. The last round petered out in January.

Still, Russia’s Foreign Ministry, in a statement Wednesday after a meeting with a senior Iranian security official, said Moscow re-affirmed the need to find mutually acceptable solutions via negotiations. Russia accepts that the West has legitimate concerns about Iran’s nuclear program but sees no clear evidence that Tehran is trying to develop nuclear warheads. Israel urged the international community to stop Iran from getting nuclear weapons at all costs.

“The significance of the [IAEA] report is that the international community must bring about the cessation of Iran’s pursuit of nuclear weapons, which endanger the peace of the world and of the Middle East,” Prime Minister Benjamin Netanyahu’s office said in a statement.

Iran has repeatedly insisted it wants nuclear energy only for electricity. On Wednesday, it vowed no retreat from the program following the U.N. watchdog report, which used Western intelligence information that Tehran calls forgeries.

“You should know that this nation will not pull back even a needle’s width from the path it is on,” President Mahmoud Ahmadinejad said in a speech carried live on state TV.

Russia’s Foreign Ministry said: “According to our initial evaluations, there is no fundamentally new information in the report … We are talking about a compilation of known facts, given a politicized tone.” It said interpretations of the report were reminiscent of the use of faulty intelligence to seek support for the U.S.-led invasion of Iraq in 2003.

In addition to U.N. sanctions that commit all countries, the United States and European Union have imposed extra sanctions of their own. A U.S. official said that because of Russian and Chinese opposition, chances were slim for another U.N. Security Council sanctions resolution against Iran.

Washington might extend sanctions against Iranian commercial banks or front companies but is unlikely to go after its oil and gas industry or central bank, the clearing house for Iran’s energy trade, for now.

Foreign Ministry spokesman Hong Lei said China was studying the IAEA report and repeated a call to resolve the row through talks. In a commentary, China’s official Xinhua news agency said the U.N. watchdog still “lacks a smoking gun.”