Ecuador has cut Julian Assange's internet connection at its embassy in London, preventing him from communicating with the outside world.
The move is to prevent the WikiLeaks founder from interfering in other countries' affairs, Ecuador said.
It comes after Mr Assange questioned accusations that Moscow was responsible for the poisoning of a Russian ex-spy and his daughter in the UK on 4 March.
Mr Assange was granted political asylum at the Ecuadorean embassy in 2012.
He was initially staying in London to avoid extradition to Sweden to face questioning over allegations of sex crimes, which the 46-year-old has always denied.
The Swedish authorities have since dropped their investigation, but Mr Assange believes he will be extradited to the US for questioning over the activities of WikiLeaks if he leaves the building.
On Monday, Mr Assange used Twitter to question the decision by the UK and more than 20 other countries to retaliate against a nerve agent attack on Sergei Skripal and his daughter Yulia in the UK city of Salisbury by expelling Russian diplomats.
(3/3) Further, while it is reasonable for Theresa May to view the Russian state as the leading suspect, so far the evidence is circumstantial & the OCPW has not yet made any independent confirmation, permitting the Kremlin push the view domestically that Russia is persecuted.
— Julian Assange (@JulianAssange) March 26, 2018
End of Twitter post by @JulianAssange
UK Foreign Office minister Alan Duncan responded to his comments by branding the Australian a "miserable little worm" who needs to turn himself over to authorities.
In 2016, Ecuador briefly suspended Mr Assange's internet connection after he published hacked emails from the campaign team of Hillary Clinton, a move seen as having an impact on the US presidential election campaign.
In May 2017, Ecuadorean President Lenín Moreno asked Mr Assange to refrain from expressing his public support for the independence campaign in Spain's Catalonia region after he tweeted that Madrid was guilty of "repression".
Mr Assange was granted asylum by President Moreno's predecessor, Rafael Correa.
Mr Moreno's government has said it will maintain Mr Assange's asylum. But it has also sought ways for him to leave the embassy without risking arrest for breaching his bail conditions, and possible extradition to the US over the 2010 publication of classified information by WikiLeaks.