An early morning tweet accused a “state party” of being responsible for shutting down internet access to Mr Assange, who has been living inside the Ecuadorian Embassy in London for over four years.
The tweet said: “Julian Assange’s internet link has been intentionally severed by a state party. We have activated the appropriate contingency plans.”
WikiLeaks did not release any more information about the incident, which attracted scores of comments on social media, ranging from concerns for the Australian’s health, to support for any move to stop the activities of the group.
The news came after WikiLeaks released another batch of emails from the campaign manager of US presidential candidate Hillary Clinton.
Mr Assange is wanted for questioning in Sweden over a sex allegation, which he denies, but he believes that if he leaves the embassy he will be extradited to the US for questioning over the activities of WikiLeaks.