"So far we heard nothing more from them," Swedish prosecutor Marianne Ny told reporters on Wednesday, after Ecuador said last month
it would allow Assange to be interrogated inside the embassy.
"We are waiting to be told how and when this interview will take place, and if we will be able to be present while it's been held," said Ny, who added that Swedish investigators are ready to travel when needed.
WikiLeaks founder Assange has been holed up at the embassy for the last four years to avoid extradition to Sweden, where prosecutors want to question him about 2010 allegations that he raped a female WikiLeaks volunteer.
The Australian-born Assange, 45, has not been charged and has denied any wrongdoing in the Sweden case.
Ecuador's Ministry of Foreign Affairs had no comment when contacted by CNN.
Time running out for prosecutors?
Prosecutors have four years left before the deadline for bringing rape charges against Assange expires in August 2020.
Three other allegations of sexual assault against the WikiLeaks founder had to be dropped
by authorities after the deadlines expired in August 2015.
Prosecutor Ny said the maximum sentence in rape cases is usually six years, though in Assange's outstanding case she estimated a potential sentence of 18 months to two years.
His years spent in the Ecuadorian embassy would not count towards any prison time, she added.
Four years in lockdown
Assange has been living in the embassy since July 2012, the same year Ecuador granted him political asylum.
The estimated cost of policing the Ecuadorian embassy between June 2012 and October 2015 was £13.2m ($17.67m ), according to London's Metropolitan Police. Officers were withdrawn from outside the embassy on October 12, 2015.
Assange has said he fears Sweden would extradite him to the United States
, where he could face the death penalty if he is charged and convicted of publishing government secrets through WikiLeaks.
There are currently no charges filed against him in the US.
Since WikiLeaks launched in 2006, it has published thousands of classified government documents, diplomatic cables and videos.
In 2007, it posted a procedures manual for Camp Delta, the US detention center in Guantanamo Bay.
Three years after that, the site posted more than 90,000 classified documents related to the war in Afghanistan.
It was described as the biggest such leak since the Pentagon Papers during the Vietnam War.
WikiLeaks has also published almost 400,000 classified military documents from the Iraq War,
providing insights into how many Iraqi civilians have been killed and accounts of abuse by Iraqi's army and police.
In July, Assange made headlines after WikiLeaks published emails and voicemails leaked from the Democratic National Committee.
Assange, who has vowed to release more information
to damage Hillary Clinton's campaign, has been doing media interviews via satellite from the Ecuadorian embassy.