Computer giant IBM continues to dominate the list - which is compiled twice a year - with a total of 232 out of the top 500 supercomputers.

Its Blue Gene/L supercomputer - used to ensure the US nuclear weapons stockpile remains safe and reliable - comes out at number one.

The Indian system - known as EKA - made it into fourth place.

The world's fastest supercomputer - BlueGene/L - has been significantly upgraded in the last six months.

It can now deliver a sustained performance of 478 trillion calculations per second (478 teraflops), nearly three times faster than any other machine on the list.