Tehran  - Iran has started to install 6,000 centrifuges at the Natanz nuclear plant in the centre of the country, official news agency IRNA quoted President Mahmoud Ahmadinejad as saying Tuesday.

"Last year tests were made on 3,000 centrifuges and we entered the phase of (uranium enrichment at) industrial level and today the phase of installation of 6,000 new centrifuges has started," IRNA quoted the president as saying.

There was confusion within the Iranian state media Tuesday over the number of new nuclear centrifuges to be installed.

The first reports quoted Ahmadinejad as saying that 6,000 new centrifuges would be installed in Natanz, but later the website of state television network IRIB corrected the number of the new centrifuges to 3,000.

But in the meantime all state media reported about installation of 6,000 new centrifuges.

It is still unclear whether Ahmadinejad referred to 6,000 as the number of new centrifuges to be installed or as the total number of centrifuges besides the 3,000 previously installed and operating.

It is also unclear whether the new centrifuges are the slower P1 or the faster P2 centrifuges which make the uranium enrichment process at least twice as fast.

Another option could be replacement of the previous 3,000 P1 with 6,000 P2 centrifuges.

On the occasion of the so-called "National Day of Nuclear Achievement," Ahmadinejad visited the Natanz site earlier Tuesday.

Iran will also hold a special ceremony on Tuesday evening in Tehran to commemorate the occasion and disclose further details on new nuclear achievements.

In Vienna, the International Atomic Energy Agency (IAEA) declined to comment on Tehran's announcement.

Diplomats in Vienna played down the significance of the announcement, and said that Iran had already in the past announced their intention of install up to as many as
54,000 centrifuges for enrichment.

US Ambassador to the IAEA Gregory Schulte said Tuesday's announcement reflected the "Iranian leadership's continuing violation of international obligation and refusal to address international concerns."

Schulte added that if Iran wanted to achieve its right to civilian nuclear power, it should comply with international obligations and accept the June 2006 offer by Europe, Russia, China and the United States.

"Today's announcement shows clear intent to even further violate Security Council requirements. Negotiation, not escalation, provides the best path to international respect and regional security," he said. (dpa)