Shanghai, China ? Iranian President Mahmoud Ahmadinejad said Friday a U.S.-endorsed incentive package was a positive step toward resolving the standoff over Tehran’s nuclear program.

Ahmadinejad’s remarks were the highest-level sign that Iran was preparing to negotiate over the package, which calls for talks with the U.S. and other incentives if Iran freezes its uranium enrichment program.

“Generally speaking, we’re regarding this offer as a step forward and I have instructed my colleagues to carefully consider it,” Ahmadinejad told reporters after meeting with Chinese President Hu Jintao in Shanghai.

In Washington, Secretary of State Condoleezza Rice called the signals from Iran encouraging.

“Certainly we have heard some positive statements from the Iranians,” Rice said following a meeting with her Italian counterpart, Foreign Minister Massimo D’Alema.

Ahmadinejad also said Iran was not afraid of an Israeli attack to stop its nuclear program. He also repeated assertions that the Nazi Holocaust was unproven, saying it should be independently investigated.

“An event that has influenced so many diplomatic and political equations of the world needs to be investigated and researched by impartial and independent groups,” Ahmadinejad said.

The hard-line president has previously dismissed the Holocaust as a “myth” and said Israel should be “wiped off the map.” His questioning of the World War II slaughter of 6 million Jews in the past has drawn scorn and condemnation from the West and Israel.

Iran has sent mixed signals about the incentive package – also backed by three European countries, Russia and China – ever since it was offered last month. On Thursday, Iran’s supreme leader, Ayatollah Ali Khamenei, was quoted on state television as saying: “The Islamic Republic of Iran will not succumb to these pressures.”

At a conference Friday in the Central Asian nation of Kazakhstan, Iran’s deputy foreign minister, Said Abbas Irakchi, told reporters that Tehran had some concerns about the proposal.

“We see a lot of positive things there, but there are some things that we don’t understand and that raise questions,” he said.

Irakchi did not say what problems Iran saw with the incentives.

Iran denies accusations by the U.S. and others that it is seeking to develop nuclear weapons, saying its program would only generate energy.