With the stage being set for a fresh showdown between Iran and Western powers, Secretary of State Condoleezza Rice said Thursday that the U.S. and its allies would use the U.N. Security Council and other "available channels" to bring Tehran back to negotiations over its nuclear program.

The International Atomic Energy Agency was expected to report Thursday that Iran has expanded uranium enrichment efforts instead of meeting international demands to halt them. The finding could lead to Security Council sanctions broader than a limited set imposed by the council last month.

In addition to the sanctions, the Bush administration has been raising the pressure on Tehran on other fronts, from arresting Iranian officials in Iraq to persuading European governments and financial institutions to cut ties with the Islamic Republic.

Rice, speaking in Berlin, said that the United States, European and Russian diplomats all want Iran back at the bargaining table.

"We reconfirmed we will use available channels and the Security Council to try to achieve that goal," she said following a breakfast meeting with her counterparts from Germany, Russia and the European Union.

The Security Council is demanding an immediate and unconditional stop to uranium enrichment, after which European-led negotiations over an economic reward package could begin. Iran, which has long insisted it will not stop its nuclear activities as a precondition for negotiations, missed a Wednesday Security Council deadline to halt enrichment.

In moderate remarks Wednesday directed at Washington — the key backer of tougher U.N. action — Iranian Foreign Minister Manouchehr Mottaki said the dispute "has to be decided peacefully with the United States."

But other top Iranian officials used harsher language, and none showed signs of compromise on the main demand of the U.S. and other world powers — a halt to enrichment and related activities.

"The enemy is making a big mistake if it thinks it can thwart the will of the Iranian nation to achieve the peaceful use of nuclear technology," Iranian state TV's Web site quoted President Mahmoud Ahmadinejad as saying Wednesday.

The IAEA planned to send its report on Iran's compliance Thursday to the agency's 35-nation board and to the Security Council.

Although any finding that Iran has ignored the deadline on enrichment would be a step toward additional sanctions, it was not clear whether U.N. Security Council members Russia and China would go along.

Rice said she and her counterparts made no decisions Thursday because they met before the report was released.

With the United States beefing up naval forces in the Gulf and cracking down on Iranians within Iraq it says are helping Shiite militias, concerns have grown that Washington might be planning military action.

In London, British Prime Minister Tony Blair said "the only sensible way" to solve the crisis was to pursue political solutions, but that he could not "absolutely predict every set of circumstances."

Still, "I know of nobody in Washington that is planning military action on Iran," Blair told British Broadcasting Corp. radio. "Iran is not Iraq. There is, as far as I know, no planning going on to make an attack on Iran and people are pursuing a diplomatic and political solution."

Tehran's refusal to freeze all its enrichment-related activities prompted the Security Council on Dec. 23 to impose sanctions targeting its nuclear and missile programs and persons involved in them. Back then, it gave the country 60 days to halt enrichment or face additional measures.

Discussions on a new resolution aimed at stepping up pressure on Iran to suspend enrichment were expected to start next week, a Security Council diplomat said in New York, speaking on condition of anonymity because of the sensitivity of the issue.

Part of the sanctions target companies suspected of involvement in Iran's nuclear program — a measure that an Iranian dissident group said Tehran was circumventing by renaming the companies and otherwise disguising them, or setting up new ones.

In a list provided to The Associated Press on Thursday ahead of general publication, the National Council of Resistance in Iran said firms under sanctions that were renamed were the Farayand Technique Company and the Pars Thrash Company. It named new companies set up to work on Iran's enrichment programs while avoiding sanctions as Tamin Tajhizat Sanayeh Hasteieh, Shakhes Behbood Sanaat and Sookht Atomi Reactorhaye Iran.

All are headed by Gholamreza Aghazadeh, head of Iran's atomic energy programs, and some involve others on the Security Council's list of those involved in Iran's nuclear program, said the group, the political wing of the People's Mujahedeen of Iran, which advocates the overthrow of Iran's Islamic government.

There was no independent confirmation of the information provided by the group, which the United States and the European Union list as a terrorist organization. But it has revealed past secret Iranian nuclear activities subsequently verified by the IAEA or governments.