Privacy advocates are concerned that a move by Verio to stop hosting a controversial open government website points to a growing control of the web by big business and governments.

Cryptome.org, a website that sometimes posts documents about government policy and intelligence, received a short letter from its internet service provider (ISP), Verio, indicating that the site would be terminated on Friday. Verio, owned by NTT Communications, said the termination is due to violation of its acceptable use policy.

Cryptome.org has run afoul of Verio's policy before but historically the ISP has allowed the site to rectify the violation either by removing a document or proving that posting the document doesn't breach any laws. This time, Verio hasn't offered Cryptome.org that opportunity and also hasn't specified how exactly the site violates the rules, said John Young, Cryptome.org's founder, in a note on the site.

Young did not respond to requests for comment about termination of the site and Verio did not respond to e-mails and phone calls asking for more information.

Cryptome.org fans have some ideas about why Verio may be shutting off the site. "If you wanted to go down the conspiracy theory route, you'd say some government agency pressured [Verio], but we don't know this," said Steve Bellovin, a professor in Columbia University's computer science department.

Cryptome.org is a "very valuable repository for people interested in open government," Bellovin said. "There are people who don't like that much openness."

According to the site, Verio has historically received requests, passed on to Young from a wide range of sources including British intelligence, asking him to remove documents from the site.

Verio may also have simply decided that supporting Cryptome.org wasn't worth the legal burden. Many of the requests for removal of documents are sent to Verio's legal team, which then must work with Young to sort out the request.

In a note to Young dating back to 2001 posted on the website, Verio's legal department warns him that accounts of repeat copyright infringers will be terminated according to the ISP's acceptable use policy.

The incident points to a potentially worrying trend, Bellovin said. A few years ago, a court opinion called the internet the purest platform for free speech that the market has ever invented, he said. "But as control of the Net gets more concentrated in the hands of big corporations, that gets less and less true," he said.

It's unclear if Young will have trouble finding another ISP to support the site. "He can get a small ISP but they are mostly dependant on big ISPs to carry their traffic," Bellovin said.

In a comment posted on news blogging and aggregation website, Slashdot about the Cryptome incident, someone purporting to be Young wrote that Cryptome will continue with another ISP in the US or elsewhere.