Ecuador has requested a meeting with Britain to discuss WikiLeaks founder Julian Assange, who it says is losing weight and suffering vision problems as he languishes in the Ecuadoran embassy in London.

Ecuadoran Foreign Minister Ricardo Patino told reporters in Quito on Wednesday that he had related his wish to meet with British counterpart William Hague to Britain's ambassador to Ecuador.

Patino said he wanted to discuss Assange's worsening health following more than four months in the embassy where he is sheltering to avoid prosecution.

Ecuador said it had asked the British government for written assurances that Assange, who has been granted asylum by Quito, will not be arrested in the event of hospitalization.

"As a result of the government of Britain not giving safe passage, Julian Assange's health most certainly is beginning to be jeopardized and this is very serious," Patino said in an earlier radio interview.

"We had hoped that the British government would defend and respect human rights and international law," said Patino, adding that he had learned that Assange is suffering from problems with his vision.

"I hope that we will not have cause to regret a serious situation there," the Ecuadoran envoy said.

The 41-year old Australian walked into the Ecuadoran embassy in London on June 19 seeking asylum in a bid to avoid extradition to Sweden, where he faces questioning over alleged rape and sexual assault.

He was granted asylum on August 16 but Britain has refused to grant him safe passage out of the country, and he remains in the embassy, putting Ecuador in a diplomatic stalemate with Britain.

Assange denies sex crimes allegations against him, and claims he could eventually be passed from Sweden to the United States for prosecution over the WikiLeaks website's publication of hundreds of thousands of classified US documents.

WikiLeaks enraged Washington in 2010 by publishing a flood of secret military files on the wars in Iraq and Afghanistan, as well as a huge cache of diplomatic cables from US embassies across the world.

Ecuador's Deputy Foreign Minister Marco Albuja also expressed concern for Assange's well-being, telling Voice of Russia radio as an Ecuadoran delegation wrapped up a Russia visit that "Assange has visibly lost weight, and we are very concerned for his health."

"In case of his illness we will have to pick among two options: to treat Mr Assange at the embassy or to hospitalize him."

Albuja said that Britain so far has not agreed to its request of safe passage for Assange, but "is thinking it over."

However, Britain's Foreign Office told AFP on Wednesday that it had not yet received a request.

"Ecuador had not told us that Mr Assange was ill. However, were they to do so we would consider the matter," a Foreign Office spokesman said.

Assange said in an interview published September 30 that his health was "slowly deteriorating" in the embassy, adding that he had "a racking cough."

He said he was keeping fit by using a running machine, boxing and working out every other day with a personal trainer -- reportedly an ex-soldier in Britain's elite SAS who is now a whistleblower.