Persian state to celebrate Tuesday's national day by heralding controversial atomic programme.
Iran on Tuesday marks its new national day celebrating the achievements of its controversial nuclear programme with speeches by top officials including President Mahmoud Ahmadinejad.
For the second year the Islamic republic is staging its "national day of nuclear achievement" commemorating the April 2006 anniversary of Iran's first production of uranium sufficiently enriched to make atomic fuel.
The West fears Iran could use uranium enrichment to make a nuclear weapon, and Tehran's refusal to suspend the process has been punished with three sets of UN Security Council sanctions and US pressure on its banking system.
On Tuesday morning Ahmadinejad is due to speak at Iran's most important nuclear facility of Natanz, where engineers have built around 3,000 P1 centrifuges at an underground facility to enrich uranium, state media reported.
Iran has in recent months also started experimenting with more efficient P2 centrifuges at an above-ground test facility at the plant - the latest example that it has no intention of giving in to Western demands to halt enrichment.
Ahmadinejad will later attend a major ceremony at 1600 GMT at the headquarters of Iranian state broadcasting in Tehran alongside the head of Iran's atomic energy organisation Gholam Reza Aghazadeh.
Some reports have said Iran has expanded the number of centrifuges at Natanz with more advanced models but this has not been confirmed by Iranian officials.
But they have also hinted that the country is preparing to announce "good news" about progress in the nuclear programme on Tuesday.
Despite the progress made in recent years, Iran is believed to have experienced difficulties in running its existing centrifuges to full capacity.
In its latest report, the International Atomic Energy Agency (IAEA) declared that "the throughput of the (enrichment) facility has been well below its declared design capacity."
Iran's ambassador to the IAEA, Ali Asghar Soltanieh, has said it was "natural in this kind of industry that there are ups and downs once in a while."
Iran insists that its nuclear programme is entirely peaceful and solely aimed at generating energy for a growing population whose supply of fossil fuels will eventually run out.
Russia is providing the fuel for Iran's first nuclear power station with a capacity of 1,000 megawatts which it is building in the southern city of Bushehr. After a series of delays, the station is due to come online later this year.
But Iran has said it wants to produce its own nuclear fuel for almost 20 new nuclear power stations it is planning to build over the next few years to supply a total of 20,000 megawatts of electricity.
Tehran has repeatedly insisted that it has no intention of making concessions over the key issue of uranium enrichment, leading to deadlock in the standoff with the international community.
"The government rejects any package of incentives that calls for the suspension of enrichment or undermines the Iranian nation's nuclear rights," said foreign ministry spokesman Mohammad Ali Hosseini.