Diplomats from six world powers are set to meet at the United Nations as the U.S. continues to push for another round of sanctions against Iran's nuclear program.
Ambassadors from the five permanent U.N. Security Council members -- Britain, China, France, Russia and the United States -- along with Germany, are scheduled to meet in New York Wednesday to discuss possible sanctions.
In a defiant move Wednesday, Iran announced it had succeeded in producing its first significant batch of more highly enriched uranium.
Iran's nuclear chief, Ali Akbar Salehi, said Tehran had enriched five kilograms of uranium to 20 percent purity. Experts say 90 percent-enriched uranium is needed to make nuclear weapons.
The Security Council members are considering punitive measures aimed at persuading Iran to stop enriching uranium.
World leaders believe Iran is secretly trying to produce nuclear weapons, a charge Tehran denies.
Iranian President Mahmoud Ahmadinejad has called on U.S. President Barack Obama to stop threatening Iran.
In an interview with Iranian state television late Tuesday, Mr. Ahmadinejad said he sent a letter to President Obama, the content of which he said will be made public soon.
Tuesday in Washington, Mr. Obama urged the international community to move "quickly and boldly" on a new set of sanctions.
Earlier this week at the nuclear security summit in Washington, White House officials said China is seriously considering new sanctions against Iran, and has assigned officials to participate in U.N. sessions on the matter. China, which has been reluctant to back new sanctions, has said it will support sanctions only if diplomacy fails.