"Any retreat at this juncture will lead to chain reactions and pressures for more compromises, so the program is irreversible," Khamenei was quoted by state television as saying.

The Supreme leader made the remarks in a speech to a group of diplomats recalled home from their posts for deliberations on the next move over the rising nuclear tension.

Khamenei said that retreat over the nuclear dispute would harm Iran's sovereignty and the interest of the Iranian people, urging diplomats to defend the country's nuclear rights.

Meanwhile, Iranian President Mahmoud Ahmadinejad said in the northern province of Golestan that Iran would never abandon the path it had chosen toward nuclear energy.

"The enemies should be confident that they cannot stop the Iranian nation on its path, not can they deprive the Iranians of their legal right through conspiracies and political pressures from outside the country or by adopting resolution against the nation," Ahmadinejad said.

Also on Tuesday, it was reported that Iran and Russian had resumed negotiations over a proposal made by Moscow that Iran would transfer its uranium enrichment to Russia to guarantee that it will not use the technology to build nuclear weapons.

The tension over Iran's nuclear issue reached an unpredictable critical stage after Iran's rejection of a resolution adopted by the International Atomic Energy Agency (IAEA) in early February which urged Iran to suspend all works related to the enrichment and fully cooperate with the agency.

The UN nuclear watchdog, also in the resolution, decided to report Iran's case to the UN Security Council but called on the powerful UN body to withhold punitive actions until the meeting in March.

However, Iran rejected the resolution, disallowing IAEA's snap inspections and resuming small-scale enrichment work in retaliation.

As a result, after the IAEA board of governors meeting concluded on last Wednesday, IAEA chief Mohamed ElBaradei's report on the Iranian nuclear issue was handed over to the UN Security Council.

Iran has denounced the involvement of the Security Council, vowing never to give in to pressures and bullies.