Two U.N. atomic watchdog officials began talks here Thursday to clear up questions about Iran's nuclear program before an Oct. 31 deadline for Tehran to prove its aims are peaceful.

The meetings between officials from the International Atomic Energy Agency (search), based in Vienna, Austria, and the Atomic Energy Organization of Iran (search) began about 10 a.m. "under an atmosphere of understanding," said Saber Zaimian, a spokesman for the Iranian group.

"The talks are very important and vital for both sides," Zaimian told The Associated Press.

Representing the IAEA was its deputy director general, Pierre Goldschmidt, who arrived Wednesday evening with another top official of the agency, Zaimian said. The Iranian participants were not identified.

Later Thursday, the Atomic Energy Organization chief's office said the talks would continue into the night.

Zaimian said the talks were expected to take "between one to three weeks, depending on the progress of the negotiations."

Before boarding a flight to Tehran, Goldschmidt said the IAEA officials were invited by Iranian Vice President Gholamreza Aghazadeh, "so I expect that he has a very important message for us and [that we will] progress very rapidly."

"We have only a few weeks to progress and report to the next board, so I expect we are going to make great progress," Goldschmidt said.

Iran's government spokesman, Abdollah Ramezanzadeh, said after a Cabinet meeting late Wednesday that Iran has formed various official committees from different state institutions to draw up Tehran's response to the IAEA's demands.

During a trip to Iran earlier this year, IAEA inspectors found traces of weapons-grade uranium (search) and signs of other questionable nuclear activity, leading the agency to impose the October deadline during a meeting of its board on Sept. 12.

The 35-nation board meets again in November. If it rules that Iran violated the Nuclear Nonproliferation Treaty banning the spread of nuclear arms, the U.N. Security Council could impose diplomatic or economic sanctions.

After the traces of weapons-grade uranium were found, Iran acknowledged the findings but said they came in on contaminated equipment that was bought abroad.

President Mohammad Khatami, quoted Thursday on Iranian state television, said that "in spite of the recent hue and cry, Iran is not worried about showing transparency in its peaceful nuclear program."

In comments that appeared to indicate Tehran was ready to cooperate, Iran's Foreign Minister Kamal Kharrazi said Wednesday that Iran would do all it could to avoid being reported to the Security Council.

Iran was working toward "providing the necessary clarifications and taking the appropriate decisions to prevent this matter from going before the Security Council," Kharrazi said on state-run television.

Kharrazi, however, warned it would be useless for Iran to allow unfettered inspections if its right to enrich uranium is not guaranteed.

Iran criticized the IAEA deadline as "politically motivated" after it was imposed following lobbying from the United States, which strongly suspects Iran is developing nuclear weapons. Iran says its nuclear program is strictly for generating electricity.