A new search engine has launched that is looking to challenge Google's place at the top of the search rankings.

Cuil, pronounced "cool", has gone live on Monday 28 July and is backed by $33 million in venture capital, as well as the technological expertise of ex-Google engineers.

The brain child of Anna Patterson, whose search technology was bought by Google in 2004 to upgrade its own system, Patterson left the company in 2006 to focus on Cuil.

Patterson says that Cuil's search index spans 120 billion web pages - and boasts that this is at least three times the size of Google's index.

As well as different technology behind the searching, and a different way for the results to be displayed, Cuil is hoping to attract traffic by promising not to retain information about its users' search histories or surfing habits.