"All parts of centrifuges are built inside Iran. Each part is built in various parts of the country. Then they are assembled at one place," said Ali Akbar Velayati, international affairs adviser to Supreme Leader Ayatollah Ali Khamenei, Iran's top authority.
The remarks were carried by Jomhuri-ye Eslami newspaper.
Velayati, echoing other top Iranian officials, brushed off the impact of sanctions and said even military action would not stop work to install more centrifuges in the Natanz uranium enrichment plant in central Iran.
"Iran's nuclear technology is native and it cannot be eliminated ... Any possible military attack cannot destroy it," Velayati said.
Meanwhile, Israeli intelligence officials estimated Tuesday that Tehran would continue to advance towards obtaining nuclear power, and that in the worst case scenario could have a nuclear bomb by the second half of 2009, although such a chance was slim.
Hanan Greenberg contributed to the report