Google has lifted the lid on a new version of its search engine, upping the ante as rivals attempt to close the gap on the search giant.

The new engine, codenamed Caffeine by Google, is aimed at delivering faster, more accurate and more comprehensive results.

The engine, available for testing at a separate web address, has been launched with Google asking developers and businesses for feedback. The website "front end" of the technology looks the same, but Google said the infrastructure was updated to index new content on the web faster.

The surge in popularity of the "real-time" web of Twitter postings and social networks such as Facebook make it important that search engines can quickly find and deliver such content in the search results for consumers.

The public testing of the new Google engine comes two weeks after Microsoft struck a deal to replace Yahoo!'s search engine with its own, called Bing. Bing has gained a percentage point or two of market share since its launch earlier this year as a "decision engine" by Microsoft, backed by extensive advertising, but Google still gets about two-thirds of US search queries, according to comScore.

Yahoo! handled about a fifth of US searches in June, and Microsoft fielded less than half of that. The partnership would bring the two companies' combined share to nearly 30 per cent, still less than half of Google's total. In the rest of the world, Google is even further ahead.

In a blog post, Matt Cutts, a principal engineer at Google and Sitaram Iyer, a staff software engineer, said: "For the last several months, a large team of Googlers has been working on a secret project: a next-generation architecture for Google's web search. It's the first step in a process that will let us push the envelope on size, indexing speed, accuracy, comprehensiveness and other dimensions.

"The new infrastructure sits 'under the hood' of Google's search engine, which means that most users won't notice a difference in search results. But web developers and power searchers might notice a few differences, so we're opening up a web developer preview to collect feedback."

In a personal blog post, Mr Cutts said that Caffeine was not specifically a response to Bing: "I love competition in search and want lots of it, but this change has been in the works for months. I think the best way for Google to do well in search is to continue what we’ve done for the last decade or so: focus relentlessly on pushing our search quality forward. Nobody cares more about search than Google, and I don’t think we’ll ever stop trying to improve."

The new engine can be tested here

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