Iranian President Mahmoud Ahmadinejad waves as he attends the opening ceremony of the 29th Annual Session of the OPEC Ministerial Council in the city of Isfahan, 450 km (280 miles) south of Tehran, June 17, 2008. (Xinhua/Reuters, File Photo)

Ahmadinejad rejected any threats against the Islamic Republic, saying the country would continue its nuclear drive.

"We expect threats and hostility from the enemies side, but we are getting stronger day by day and keep moving forward," the Iranian president said.

The United States had indeed injected some hope of progress at the nuclear talks by sending Burns to the one-day meeting in Geneva, which was the highest-level contact between Tehran and Washington since 1979.

On Sunday, Iranian Foreign Minister Manouchehr Mottaki said that the presence of U.S. representative in Geneva talks prepared an opportunity for Washington to become aware of Iran's views directly.

"Such a move by the U.S. administration can be considered a positive measure," IRNA quoted Mottaki as saying.

Hassan Rowhani, Iran's former top nuclear negotiator, also said on Sunday that the presence of U.S. special envoy in Iran nuclear talks in Geneva was regarded as a U-turn in U.S. diplomacy.

"The shift in U.S. diplomacy has created a very good opportunity for Iran and we should do our best to make use of it," he said.

However, the White House has reiterated that Washington would not join full-blown talks unless Iran gave up uranium enrichment activities.