WikiLeaks' domain name system provider says it has withdrawn service to the wikileaks.org name after apparent attacks on its website.
EveryDNS says it dropped the website late on Thursday after it became the "target of multiple distributed denial of service attacks".
The American provider - which offers access to 500,000 websites - said in a statement that it dropped the site because the hacker attacks threatened the rest of its network.
"Wikileaks.org has become the target of multiple distributed denial of service attacks. These attacks have, and future attacks would, threaten the stability of the EveryDNS.net infrastructure," it said in a statement.
WikiLeaks confirmed the drop on its Twitter account, saying: "WikiLeaks.org domain killed by US everydns.net after claimed mass attacks."
WikiLeaks has angered the US and other governments by publishing almost half a million secret documents about the wars in Afghanistan and Iraq. The latest batch contains thousands of classified US diplomatic cables.
On Wednesday, Amazon - which had provided WikiLeaks with use of its servers to distribute embarrassing State Department communications and other documents - evicted it. The site remains on servers of a Swedish host, Bahnhof.
US senator Joe Lieberman praised Amazon's action and said it should "set the standard" for companies WikiLeaks is using to distribute "illegally seized material".
WikiLeaks responded to the move from EveryDNS by moving to a Swiss domain name, wikileaks.ch.
The founder of WikiLeaks, 39-year old Australian Julian Assange, has been out of sight for nearly a month, while Sweden has issued a Europe-wide arrest warrant for him over allegations of rape, sexual molestation and unlawful coercion. He may also face US prosecution on spying charges.