Assange claims he was tortured in UK prison - media
"I was detained without official charges. I spent five days without charges in a horrible prison in the UK. My health was very poor then, and they applied electricity to my shins," Assange was quoted as saying during the joint press conference with Ecuadorian Foreign Affairs Minister Ricardo Patino on Thursday.
Ecuador vowed asylum offer to Assange was for the long term.
"We will protect Julian Assange as long as necessary and as long as he wants," Patino said.
Britain's Supreme Court ruled in 2012 to extradite WikiLeaks founder to Sweden over alleged sex crimes, although WikiLeaks spokesman Kristinn Hrafnsson said he clearly saw Washington's hand in the ruling.
The United States is believed to be seeking retribution for the leakage of diplomatic cables, which can be punishable with a death sentence.
Ecuador granted political asylum to Mr. Assange in August 2012, saying there were indications of political persecution against him.
The UK refuses to allow Assange safe passage out of the embassy - ensuring round-the-clock security.
Last year, British foreign chief William Hague and his Ecuadorian counterpart, Ricardo Patino, held talks that resulted in the creation of a working group to find a diplomatic solution to Assange's problem.