An Internet service provider with links to Eastern Europe has been unplugged after it was suspected of being behind computer intrusions at NASA and sending massive amounts of malicious spam, the Federal Trade Commission said on Thursday.

Pricewert, which an FTC expert called the worst ISP in the United States in terms of hosting malicious content, was ordered disconnected on Tuesday, without notification, according to court papers.

It was unplugged on Wednesday and the order was unsealed that evening, said Ethan Arenson of the FTC's Bureau of Consumer Protection.

Twenty-two separate attacks on NASA computers were traced back to Pricewert computers, including one in April, the FTC said in its complaint to the U.S. District Court in the Northern District of California. Several of these attacks involved efforts to conscript NASA computers into a botnet, the complaint said.

A botnet is a ring of computers whose unsuspecting owners have no idea their machines are being used for spam or criminal activity.

Pricewert recruits and colludes with criminals seeking to distribute illegal, malicious and harmful electronic content via the Internet, the FTC said in its complaint. This content includes a witches' brew of child pornography, botnet command and control servers, spyware, viruses, Trojans, phishing-related sites, and pornography featuring violence, bestiality and incest.

Experts contacted by the FTC visited sites hosted by Pricewert and found a program designed to steal user names and passwords for online bank accounts, programs designed to hijack users to malicious websites, and other evidence of illegal activity.

The FTC complaint included a transcript of a chat, translated from Russian, in which a so-called bot herder, who controls hijacked computers, offers Pricewert a network of 20,000 computers which were online at that moment and another 180,000 which were compromised.

200,000 bots reached today, 15 percent of them are USA-Europe Australia, the herder says. Bots are waiting for you.

The FTC was not able to identify who controlled Pricewert, which reports its principal place of business as Belize City. While it claims to be based in the United States, the FTC said all the employees located were in the Ukraine or Estonia.

(Reporting by Diane Bartz; Editing by Richard Chang)