The Australian has been holed up in the embassy since June 2012, when he took refuge there to escape extradition to Sweden to face a rape accusation.
Ecuador's attorney general's office said the judicial procedures would begin on October 17th although the questions submitted by the Swedish prosecutors would not necessarily be put to him on the same day.
Ecuadoran prosecutor Wilson Toainga has been tasked with taking Assange's statement, it said.
“Toainga will take the statement based on a list of questions submitted by the Swedish justice ministry,” the office said, adding that he also would be responsible for “the possible taking of samples of body fluids” from Assange.
Two Swedish officials – Ingrid Isgren and Cecilia Redell – have been authorized to be present during the proceedings, it said.
Assange, 45, who denies the rape accusation, has said he fears the Swedes will turn him over to the United States to face charges for publishing a massive trove of US military and diplomatic documents.
In May, a Swedish court reaffirmed an international arrest order against Assange, rejecting the finding of a UN working group that his confinement in the Ecuadoran embassy amounted to arbitrary detention. Britain also rejected the finding of the UN group, which is not binding.
The Svea Court of Appeal is to decide on Friday whether or not to uphold the arrest warrant.