The big prize is control over the results generated by internet search engines — the means by which 80 per cent of users first discover a website.

With 600 million searches undertaken each month in Britain alone, companies will pursue any method, including some deemed underhand, to gain maximum visibility on the pages operated by the likes of Google, Yahoo and Microsoft.

Google, the search engine giant, signalled the first round of the battle this week after blacklisting the German site of BMW and yesterday Ricoh, the Japanese photocopier and office equipment manufacturer. Google found the carmaker guilty of employing a “dummy” website stuffed with keywords, which persuaded Google’s computers to place it at number one in its ranking of relevant sites.

Most of Google’s 100 million daily users consider it a trusted source of unbiased information. But the result of a search query is often manipulated for commercial benefit by web experts employing what is known as “black hat” techniques.

Duplicate “mirror” sites, for example, can trick a search engine into thinking that a site is more popular than it is.

The top result of a Google search for “liar” is now Tony Blair’s biography on the official Downing Street website. This happened after anti-war “Google-bombers” set up hundreds of sites establishing a link. They exploited Google’s policy of looking at not just the content of a page but also on how often a site is linked to others and with what words.

BMW had set up a “doorway” web page, which used the German expression for “used car” 42 times. Packing the page with car “keywords” convinced search engine computers that it was the top destination for potential used car buyers.

Search engines such as Google, AltaVista and Fast Search employ high-tech “spiders” that crawl across the web to collect keyword matches.

There is no standard practice across their websites to prevent companies from manipulating search results and they closely guard their techniques.

But Google is publicising a new weapon that it is about to unleash on the “black hats”.

The company is testing Big Daddy, an all-powerful new computer infrastructure, which promises to weed out attempts to cheat the system.

“We’ve had a sneak preview and it’s a major advance,” said Grant Whiteside, technical director of Ambergreen, an internet marketing company. “It can detect if a web page is the original or a duplicate and should stop customers being directed to pornography through ‘hijacked’ web pages. But that won’t stop the search marketing business trying to beat it.”

Big Daddy is expected to be up and running as early as next month. But the practice known as search engine “optimisation” — getting search engines to place your website prominently — has become a cut-throat business with 81 per cent of internet customers finding products through searches.

Mr Whiteside said: “It is essential to get your website on to page one of the search results because very few people go beyond that. But there isn’t a set of rules across search engines so the system is open to abuse.” Andrew Redfern of Latitude, Europe’s largest search engine specialists, said: “There are unethical companies who will get you to number one in the Google chart but you will be cast out for six months.

“The message Google wants to send is this, ‘If it can happen to BMW, it can happen to you. So if you’re not in compliance, clean up your act’.”

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