It is unknown how many third-generation centrifuges Iran could build

Iran's president has unveiled new “third-generation” centrifuges that its nuclear chief says can enrich uranium much faster than current technology.

The centrifuges would have separation power “six times that of the first generation”, Ali Akbar Salehi said in a speech marking National Nuclear Day.

Uranium enrichment is the central concern of Western nations negotiating with Iran over its nuclear programme.

The technology can be used to make fuel for power plants and nuclear weapons.

The new centrifuges would be more advanced than the P1 model – reportedly acquired on the black market in the 1980s and prone to breakdowns – in use at the Natanz enrichment facility.

In October, Mr Salehi announced that a second generation of centrifuges, developed by Iranian scientists and most of whose components were made domestically, would be installed at Iran's previously secret facility near Qom.

BBC Tehran correspondent Jon Leyne, who is in London, says nuclear experts point out that the key question is how many of the third-generation centrifuges Iran can produce.

There have already been many problems with the existing model, so whether Iran can quickly put the new one into mass production and operation remains to be seen, our correspondent says.