TEHRAN (AFP/Reuters) - Iran said it will soon begin mass production of centrifuges capable of enriching uranium, the most controversial part of its nuclear programme, three times faster than existing systems. Atomic chief Ali Akbar Salehi said the Islamic republic also now possessed the technical know-how to manufacture the fuel pellets required to power atomic reactors. The mass production of second generation centrifuges will begin in the coming months, Salehi said on state television late Saturday. On Friday Iran unveiled a third generation centrifuge it said can enrich uranium six times faster than the IR-1 system at its plant in the central city of Natanz. The Natanz facility has a capacity of 60,000 centrifuges, and Iran has been steadily enriching uranium there for years in defiance of three sets of UN sanctions and threat of a fourth. The enrichment method used by Iran is a classic type in which uranium hexafluoride (UF6) gas is whizzed around in a centrifuge at supersonic speeds to separate the precious U-235 isotope from the denser U-238. Salehi said Iranian scientists would inject UF6 gas in the third generation centrifuge in few months, adding however, maybe it needs a year for us to witness a chain of them. Once our appraisal of third generation (centrifuges) is complete and we reach its mass production, the manufacture of the second generation machine will be stopped. Salehi dismissed Western claims Iran lacked the know-how to make the fuel pellets required to power a reactor, such as its Tehran research facility. They said: you cant make pellets. But now I can say with certainty that we have the technical knowledge to make fuel pellets, Salehi said. Russia and France are ready to supply fuel for the Tehran reactor if Iran ships its low-enriched uranium abroad, but the UN-drafted deal is deadlocked over differences between the two sides. Iran has defiantly started producing the fuel itself, but France says Tehran lacks the technology to convert the material into the fuel pellets needed for the facility which makes medical isotopes. Salehi said Iran was close to mastering the fuel pellet technology and on Friday the Islamic republic unveiled what it claimed was a virtual model of the pellets using copper. We are going slowly. In the next stage instead of copper as virtual fuel we will use a material close to uranium and in the following stage we will use uranium itself, he said, adding the pellet manufacturing facility was also nearly ready. If the Western countries had not created problems, we would have been able to export radioisotopes by now from the Tehran reactor, he said. Salehi said to prevent such obstacles, Iran was building the 40 MW heavy water reactor in the central city of Arak. It will be online in three to four years, he said. Meanwhile, the defence ministry said Iran had started producing a prototype of an advanced anti-aircraft missile system. The Mersad air defence system ... is able to destroy modern aircraft at low and medium range altitude, the ISNA news agency on Sunday quoted Defence Minister Ahmad Vahidi as saying. The mass production of this product has begun and in the course of the current year a large number of them will be delivered to the armed forces, he said. While Iran hopes the development of its own system will make it more self-sufficient in weapons defence, it is also urging Russia to resist Western pressure not to deliver the S-300 missile defence system it has ordered.