Iran will retaliate against any attack by Israeli or US forces, the country's supreme leader has said in a defiant address made shortly after US President Barack Obama had issued a message directly to the Iranian people.
Both Ayatollah Ali Khamenei and Obama were speaking on Tuesday to mark Nowruz, the Persian new year, with Khamenei reiterating once again that his country did not intend to build nuclear weapons.
"We do not have nuclear weapons and we will not build them but in the face of aggression from the enemies, whether from America or the Zionist regime, to defend ourselves we will attack on the same level as the enemies attack us," Khamenei said in a speech broadcast on state television.
"Americans are making a grave mistake if they think by making threats they will destroy the Iranian nation," he said.
Israel and the US have threatened military action against Iran unless it abandons nuclear activities which the West suspects are intended to develop nuclear weapons.
Further talks between Iran and the P5+1 group of countries (the permanent five members of the UN Security Council plus Germany) are expected to take place next month in an attempt to reach a compromise deal.
The most recent talks between world powers and Iran failed in January 2011 because of Iran's refusal to suspend its sensitive uranium enrichment work, as demanded by several UN resolutions and major powers.
It says it has the right to develop a peaceful nuclear programme as a signatory to the international nuclear non-proliferation treaty.
In his speech, Khamenei highlighted the country's nuclear achievements over the last 12 months; namely, increasing uranium enrichment to 20 per cent and loading domestically-made fuel rods at a Tehran research reactor.
"In a situation where the enemies were putting bets on the fall of the Iranian nation, and talking about the crippling sanctions, Iran has accomplished all these achievements," he added.
The US and its allies have imposed tough new sanctions on Iran since this year which western diplomats say show signs of having a strong effect on the Iranian economy.
Timothy Geithner, the US treasury secretary, said on Tuesday that Washington would keep looking for ways to effectively put pressure on Iran and was getting help from Europe, Japan, China and South Korea.
"We have had much broader co-operation even beyond Europe because you're seeing Japan, South Korea, China and countries around the world really moving with us to tighten up" sanctions against Iran, Geithner told a congressional committee hearing.
Obama on Tuesday made a direct appeal to the Iranian people, saying there was "no reason for the United States and Iran to be divided from one another".
In a video message, also marking Nowruz, Obama said the US sought a dialogue with the Iranian people in order to hear their views and understand their aspirations.
Obama said the Iranian government had established an "electronic curtain" around its people, blocking their access to much of the outside world.
"Increasingly, the Iranian people are denied the basic freedom to access the information that they want," Obama said. "Instead, the Iranian government jams satellite signals to shut down television and radio broadcasts.
"It censors the Internet to control what the Iranian people can see and say. The regime monitors computers and cell phones for the sole purpose of protecting its own power."
The president has often sought to use the occasion of Nowruz to attempt to draw a distinction between the Iranian people and the government in Tehran.