London is the zombie capital of the world, with approximately 150,000 PCs secretly controlled by hackers, Symantec has revealed.

And the UK - thanks mostly to the rapid growth of broadband - is officially the worst bot-infected place on the globe. Somewhat bizarrely the obscure city of Winsford in Cheshire is the world's second biggest hotspot for zombies, according to Symantec, followed by Seoul in Korea.

The anti-virus company estimates that nearly a third of the between one and two million computers worldwide infected with the bot software are now located in the UK. Eight percent of them alone are in London, according to Dean Turner, senior manager of the Symantec Security Response team.

"Bot networks are valuable for a couple of reasons: One, because they allow for extremely rapid propagation, and two, because they provide a relatively high level of anonymity for providing attacks," he said.

On average more than 10,000 bot-infected machines were active each day during the first six months of the year, an increase of more than 140 percent over the preceding six months, according to Turner.

These networks of zombie computers have become a weapon of choice for spammers and phishers as well as attackers looking to swamp a victim's server with a denial of service attack.

The US and China were the second-largest and third-largest providers of bot-infected systems, with 19 percent and 7 percent, respectively.

London is considered one of the largest hub cities on the Internet, with a total of 1.1Tbit/s of international bandwidth available in the city.

Use of DSL (digital subscriber line) broadband has been growing rapidly throughout the UK. Earlier this year, BT announced that it had more than doubled its DSL connections over the previous year's number, reaching a total of five million lines 12 months earlier than expected.