Ecuadorean embassy officials say they have had no contact with the UK for a week, after the country granted asylum to Julian Assange.
Mr Assange has been at Ecuador's London embassy since June in a bid to avoid extradition to Sweden over sex assault claims, which he denies.
Officials also told an embassy briefing it would be an indication of "good faith" if Britain withdrew its "threat" to arrest the Wikileaks founder.
The UK insists it must extradite him.
It had said it had a "legal obligation" to see that Mr Assange was sent to Sweden, where prosecutors want to question him, and indicated that the Diplomatic and Consular Premises Act 1987 provided it with powers to enter the embassy to arrest him.
The UK has repeatedly made clear he will be arrested if he leaves the embassy - several police officers were stationed outside on Thursday - but that it hopes for a "diplomatic solution".
Meanwhile, Ecuador's president, Rafael Correa, has said the diplomatic row over Mr Assange "could be ended tomorrow" if Britain gave him safe passage to Ecuador, in an interview with the BBC.
During the London embassy briefing, officials said they were hopeful a "compromise" could be found but said the 41-year-old Australian could stay inside the London embassy for "as long as it takes".
"He can stay here for eight years... two centuries. However long he wants," said one.
The officials said they were "surprised" the UK government had not withdrawn its "threat" to enter the embassy. It was not a condition of talks being held, but would be an "indication of good faith".
A Foreign Office official called the embassy a week ago after Mr Assange was granted asylum, but there has been no contact since.
One official added: "The Foreign Office has been contacting many South American countries in the past week indicating they wanted to open conversations again with the Ecuador government - but they have made no approach."
Foreign ministers from across South America are due to meet on Friday to discuss the situation.
On the eve of the meeting, the UK Foreign Office said it was to send the Ecuadorean embassy an official letter, though it declined to say what it contained.
In a statement, the FCO added: "As we made clear, we remain committed to a diplomatic solution."
Meanwhile, details have emerged of the actions staff at the embassy took when Mr Assange arrived there without warning on 14 June.
An air bed had to be brought from the home of the Ecuadorean ambassador so Mr Assange could sleep in one of the rooms in the ground floor of the building.
Officials said it was a "big surprise" when he arrived.
They said that up to 50 police officers arrived at the embassy last week soon after it was revealed the UK had notified Ecuador of its powers to withdrew the embassy's diplomatic status and enter the building - with some climbing a fire escape and one standing outside a toilet.
Officials said they had a "business" relationship with Mr Assange, adding that life at embassy had now returned to normal.
Sex assault claims
The UK Supreme Court in May dismissed Mr Assange's bid to reopen his appeal against extradition and gave him a two-week grace period before extradition proceedings could start.
The US is carrying out an investigation into Wikileaks, which has published a mass of leaked diplomatic cables, embarrassing several governments and international businesses.
In 2010, two female ex-Wikileaks volunteers accused Mr Assange of committing sexual offences against them while he was in Stockholm to give a lecture.
He claims the sex was consensual and the allegations are politically motivated. He says he fears extradition to the US if extradited to Sweden because of his website's publication of confidential documents.