Google is having to defend its data policy on both sides of the Atlantic.

The EU drummed the web company in April for its policy of keeping visitors' data for as long as 18 months - a whole year longer than European authorities deemed necessary.

Now groups in the US have joined together to accuse Google of violating Californian privacy law.

Google has been criticised for not providing a direct link to its privacy policy on its homepage.

However, the web company is arguing that its policy is already easy to find (through clicking on About Google) and it gives "accessible information".

Californian law requires that any commercial website that collects personal information about its users to "conspicuously post its privacy policy on its website", says the Beeb.

Pressure groups, following on from a series of blogs in the New York Times, claim that Google is not meeting this criteria.

The groups involved include the Electronic Privacy Information Centre, the World Privacy Forum, Consumer Action, the Electronic Frontier Foundation and the ACLU of Northern California.

They have now sent a letter to Google and say they want "a constructive dialogue".

In a statement, Google responded that it "ran an ad campaign to draw consumers to our privacy information, posted several blogs that explain our privacy practices in detail and posted detailed frequently-asked questions to help consumers understand the complex aspects of privacy".