Assange, a journalist of Australian nationality and founder of the WikiLeaks website which published leaked secret documents, has been suffering deep pain in the right shoulder for the last three months, disclosed Ecuador Foreign Minister Ricardo Patiño in a press conference.

His doctor has asked him to undergo a magnetic resonance imaging scan to make an accurate diagnosis, which can only be carried out in a medical facility with suitable equipment, he added.

He further said the Ecuador government had asked the British government "for a safe passage for humanitarian reasons (...) so that Assange can get an MRI," but was turned down.

"He (Assange) can leave whenever he likes for any medical care he might need but the European arrest warrant for Assange is still valid," he read from the missive sent by the British authorities in response.

The reply is equivalent to saying Assange "can leave - and we will put him in jail," the moment he steps out of the diplomatic premises, Patiño said.

According to him, such humanitarian concessions have been granted even in times of war and conflict.

Expressing concern over the state of Assange's health, he said, "I hope that we will not have cause to regret a serious situation there."

Assange took refuge in the Ecuadorian Embassy after losing a long battle in British courts to avoid extradition to Sweden for questioning on allegations of sexual misconduct.

He had argued there was a real threat of onward extradition to the United States where he could face the death penalty for having leaked U.S. classified information.

While Ecuador granted Assange political asylum, Britain has denied him safe passage to leave the country, citing legal obligation to arrest and extradite him to Sweden.