Ambassador Ana Alban said Assange, who sought refuge at the embassy while fighting British efforts to extradite him to Sweden, was suffering from living "in a confined space," the BBC reported Thursday.
When Ecuadorian officials previously sought assurances Assange would not be arrested if he were hospitalized, British officials had said they wouldn't prevent "any medical care that he requires."
Assange, 41, has been living at the embassy since June and was granted asylum by Ecuador in August. The Australian, who violated terms of his bail by staying at the diplomatic compound, faces arrest if he leaves.
He is wanted for questioning in Sweden on two women's allegations of rape and sexual assault, which he denies, and was arrested in Britain on an extradition warrant. Assange's legal efforts not to be extradited to Sweden have failed.
"Mr. Assange, as everyone knows, is in a confined space," Alban said. "Not only does the embassy have few windows but the city is also dark at this time -- we have very little daylight in London. He is exposed to any health consequences from this lack of sunlight and lack of fresh air."
She said Ecuador was "waiting for a meeting" with either British Foreign Secretary William Hague or Home Secretary Theresa May to discuss the situation, the BBC reported.
The whistle-blowing WikiLeaks website has published sensitive U.S. diplomatic and military information. Assange said he fears he will be sent to the United States, where an Army private awaits court-martial on charges he passed along sensitive information to Assange, if he were extradited to Sweden.