Foreign Minister Ricardo Patino also said that Ecuador's government would announce on Thursday its decision on whether it would grant Assange's request. The Wikileaks founder took refuge in Ecuador's embassy on June 19 to avoid extradition to Sweden, where he faces questioning for alleged sexual misconduct.
Speaking in Quito, Patino charged that Ecuador received from Britain "a written threat that it could assault our embassy" if Assange was not handed over. He added that the missive was delivered to Ecuador's Foreign Ministry in writing and verbally to its ambassador in London on Wednesday.
Patino said Ecuador "rejects in the most energetic terms the explicit threat of the official British communication."
Britain's Foreign Office said in a statement late Wednesday that it had "drawn the Ecuadorians' attention to relevant provisions of our law," including the rules which govern the legal status of diplomatic missions in the United Kingdom.
The statement didn't elaborate, but Britain's 1987 Diplomatic and Consular Premises Act does allow British officials to revoke the diplomatic status of a building if the foreign power to which it belongs "ceases to use land for the purposes of its mission or exclusively for the purposes of a consular post."
"We have an obligation to extradite Mr. Assange and it is only right that we give Ecuador (the) full picture," the statement said, before adding: "We are still committed to reaching a mutually acceptable solution."
Analysts in Ecuador expressed serious doubts that Britain would seriously threaten to raid the embassy.
Professor Julio Echeverria of Quito's FLACSO university said Britain "has a long establish tradition in Europe of respecting diplomatic missions," which under international law are considered sovereign territory.
A former Ecuadorean ambassador to London, Mauricio Gandara, told The Associated Press "I refuse to believe in this threat because if asylum is granted the British government will not grant safe passage and Mr. Assange could be in the embassy for a long time."
President Rafael Correa, who has expressed sympathy for Assange, said Monday that he hoped to announce a decision this week on the asylum request and Patino said high-level consultations had occurred with Britain and Sweden.
The Australian, whose publishing via the Internet of thousands of sensitive U.S. documents including diplomatic cables and military dispatches, says the charges against him are trumped up and that he believes the U.S. has secretly indicted him and would extradite him from Sweden.