Assange, who is Australian, has sought asylum in Ecuador as he seeks to avoid extradition from Britain to Sweden, where he is accused of sexual assault. Assange has expressed a fear that if he is sent to Sweden, the United States will seek to have him extradited in the investigation into WikiLeaks' release of hundreds of thousands of leaked diplomatic documents.
Ecuadorian Foreign Minister Ricardo Patino said a British Embassy official in Quito, Ecuador, delivered a letter outlining Britain's position regarding Assange, The Guardian reported.
"You need to be aware that there is a legal base in the U.K., the Diplomatic and Consular Premises Act 1987, that would allow us to take actions in order to arrest Mr. Assange in the current premises of the embassy," the letter said. "We need to reiterate that we consider the continued use of the diplomatic premises in this way incompatible with the Vienna Convention and unsustainable, and we have made clear the serious implications that this has for our diplomatic relations."
Patino told reporters at a news conference Ecuador would announce its decision on Assange's request Thursday morning, the British newspaper said.
An unidentified spokesman said the Ecuadorian government was "deeply shocked by the British government's threats against the sovereignty of the Ecuadorean Embassy and their suggestion that they may forcibly enter the embassy."
"This a clear breach of international law and the protocols set out in the Vienna Convention," the spokesman said. "Throughout out the last 56 days Mr. Julian Assange has been in the embassy, the Ecuadorian government has acted honorably in all our attempts to seek a resolution to the situation.
"This stands in stark contrast to the escalation of the British government today with their threats to break down the door of the Ecuadorian Embassy.
"Instead of threatening violence against the Ecuadorian Embassy, the British government should use its energy to find a peaceful resolution to this situation which we are aiming to achieve."
A British Foreign Office spokeswoman said Britain "has a legal obligation to extradite Mr. Assange to Sweden to face questioning over allegations of sexual offenses and we remain determined to fulfill this obligation."
2014: The Year in Music [PHOTOS]