WASHINGTON — Iran will continue to defy demands to prove its nuclear program is peaceful unless it is hit with a new round of UN sanctions, US Secretary of State Hillary Rodham Clinton said Friday.Speaking at a news conference with new British Foreign Secretary William Hague, Clinton said negotiators from Germany and the five permanent members of the UN Security Council were making "progress every day" on a draft sanctions resolution.She said Iran's intransigence on the nuclear issue is the strongest argument for a fourth round of sanctions. "We believe that the case is being made perhaps most effectively by the Iranians themselves," she said."Every step along the way has demonstrated clearly to the world that Iran is not participating in the international arena in the way that we had asked them to do and that they continued to pursue their nuclear program," Clinton told reporters."I believe that we will not get any serious response out of the Iranians until after the Security Council acts," she said.Da Silva in TeheranHer comments came ahead of a weekend visit to Iran by Brazilian President Luis Inacio Lula da Silva, who opposes sanctions and is trying to broker a compromise with the Iranian leadership.She predicted that Silva's mediation effort would not succeed.Brazil and Turkey, both elected members of the Security Council, are trying to bring Iran back to the table without the threat of sanctions. Turkey's president is scheduled to visit Iran next week.Clinton said that Russian President Dmitry Medvedev, whose country was long opposed to sanctions but is now involved in helping craft a new resolution, had told Silva that his mission had no more than a one-in-three chance of success.Medvedev and Silva met in Moscow on Friday ahead of the Brazilian leader's trip to Teheran. Commenting on Silva's trip, Medvedev said "maybe it is the last chance before the adopting of known decisions in the Security Council."Russia is one of the five veto-wielding permanent security council members, along with the US, France, Great Britain and China.The Medvedev-Silva meeting "illustrated the hill that the Brazilians are attempting to climb," Clinton said.Meanwhile, diplomats at the UN's International Atomic Energy Agency in Vienna said Friday that Iran has set up new equipment that could let it produce more enriched uranium from a smaller amount of raw material.The step could eventually make it easier for Iran to produce a nuclear bomb and is likely to give the US more leverage with Russia and China in its push for sanctions.Clinton spoke earlier this week with Chinese State Councilor Dai Bingguo. She said Friday that she believed China, the most resistant permanent council member to sanctions, was coming around."This is the highest priority not only of the United States but of many of our partners and allies," she said.