Yahoo has admitted that it granted the US Government access to its search engine's databases this summer, as a battle develops over the right to privacy in cyberspace.

Google, by contrast, promised last night to fight vigorously the Bush Administration’s demand to know what millions of people have been looking up on the internet.

It emerged this week that the White House issued subpoenas to a number of US-based search engines this summer, asking to see what information the public had accessed in a two-month period. It said that it needed the information in order to help create online child protection laws.

But Google refused to comply with its subpoena - prompting the US Attorney General this week to ask a federal judge in San Jose for an order to hand over the requested records. Details of the confrontation emerged after the San Jose Mercury News reported seeing the court papers on Wednesday.

At the heart of the battle is the potential for online databases to become tools for government surveillance.

Yahoo has stressed that it didn’t reveal any personal information. "We are rigorous defenders of our users’ privacy," Yahoo spokeswoman Mary Osako said last night. "In our opinion, this is not a privacy issue."

The Google court papers show that the US Government originally asked for a list of all requests entered into Google’s search engine between June 1 and July 31 last year. When Google argued, the request was whittled down to a week's worth of search terms - a breakdown that could nonetheless span tens of millions of queries. In addition, the White House has asked for one million randomly selected Web addresses from various Google databases.

Every other search engine company served similar subpoenas by the Bush administration has complied so far, according to the court documents.

The co-operating search engines were not identified. Microsoft's MSN, the third-most used search engine, has declined to say whether it received a subpoena. "MSN works closely with law enforcement officials worldwide to assist them when requested," the company said in a statement.

The US Government says that it is not seeking any data that would allow it to identify which individual made which search request.

Experts say nonetheless that the subpoena raises serious privacy concerns, especially after recent revelations that the White House authorised civilian phone-taps after the September 11 attacks without obtaining court approval.

Beth Givens, director of the Privacy Rights Clearinghouse charity in California, called the subpoenas "the first shoe dropping" that online privacy advocates had long feared.

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