Of all of General Pervez Musharraf's claims in his book In the Line of Fire, one of the tallest seems to be that "there is a strong probability" the Indian uranium enrichment programme "may also have its roots" in the AQ Khan nuclear smuggling network. In other words, the Indian system is based on a Pakistani design which, as is well known, is based on a Dutch system stolen by Khan in 1976.
India is known to have a pilot plant at Bhabha Atomic Research Center in Mumbai since the mid-1980s as well as a larger plant in Ratehalli near Mysore, but the technology used and its origins are top secret.
Analysing the programme in 2004, physicist MV Ramana noted that "there have been few indications of the technological characteristics of the Ratehalli enrichment plant". The plant that went into stream in the mid-1990s is reportedly used to produce enriched uranium for India's nuclear submarine project, which is nearing completion, and is a military facility that has been kept out of the civil list in the recent separation programme listed for the Indo-US nuclear deal.
On Monday, a Department of Atomic Energy spokesman denied Musharraf's charge, saying the Indian technology is indigenous and that India is a "responsible" country, implying that it has not tapped any nuclear smuggling network.
According to a nuclear scientist, who refused to speak on record, all gas centrifuge designs have the same generic characteristics and it is impossible to establish their direct parentage unless one views the machine at close quarters.
He said that while there are several experimental laser enrichment programmes around the world, most commercial uranium enrichment takes place through the basic gas centrifuge design developed by former German PoW in Russia Gernot Zippe. This was used by Dutch company URENCO, where Khan worked as a consultant and from where he stole the blueprints.
Ramana's survey came up with little information, though he did cite a US study pointing out that several hundred centrifuges "made of domestically-produced maraging steel" were operational by the early 1990s.
Uranium enrichment is a process where the proportion of the uranium's U235 isotope is increased as against that of the U238 isotope by separating the isotopes.
There are several methods for this. The oldest technique - the one used to make the Hiroshima bomb - used an electromagnetic process to separate the isotopes; another process that was later abandoned used thermal diffusion.
Through the 1950s and 1960s, the most popular process was gaseous diffusion, where gas was forced through a semi-permeable membrane to aid separation. There are several advanced laser-based processes though they have not been commercialised.