The United Nations expert on privacy has met with Wikileaks founder Julian Assange in a London jail, saying there are strong indications the Australian's privacy may have been breached while he was holed up in the Ecuadorian embassy.

Key points: Assange complained to the UN that his privacy had been violated by the Ecuadorian embassy

Assange complained to the UN that his privacy had been violated by the Ecuadorian embassy Ecuador accused Assange of using the embassy as a centre for spying

Ecuador accused Assange of using the embassy as a centre for spying Assange faces a US extradition request over allegations he conspired with Chelsea Manning

Assange, 47, has been behind bars at the high-security Belmarsh Prison in south-east London since April 11 when he was dragged from the embassy he had called home for almost seven years.

In late March Assange complained to the UN that his privacy had been violated by the Ecuadorians and Joe Cannataci, the UN's Special Rapporteur for Privacy, was scheduled to meet Assange at the embassy.

Joe Cannataci says Assange's privacy may have been breached. ( Lateline )

Instead the two hour-long meeting took place at the prison on Thursday morning local time.

"All I can say is that he was in fairly good shape and certainly very cogent in replying to our questions," Professor Cannataci told the ABC outside the prison.

"There are strong indications that some elements of his privacy may have been breached."

Professor Cannataci would not go into details of the alleged privacy infringements but described them as wide-ranging and said he would now seek to corroborate the Australian's claims.

Spying allegations

Assange complained to the UN that the Ecuadorians violated his privacy. ( Reuters: Henry Nicholls )

Just a day before Assange's arrest WikiLeaks claimed he had been the victim of sophisticated spying operation inside Ecuador's London embassy.

Ecuador has denied the allegations, and in turn accused Assange of using the embassy as a centre for spying.

The Office of the High Commissioner for Human Rights (OHCHR) is investigating whether the Ecuadorians breached Article 12 of the Universal Declaration of Human Rights and Article 17 of the International Covenant on Civil and Political Rights.

After his arrest Assange was found guilty of skipping bail in Westminster Magistrates Court, where the judge described him as a "narcissist".

He is currently awaiting sentencing and could face up to a year in prison.

A 'special set of circumstance'

Julian Assange spent seven years holed up in the Ecuadorean embassy in London. ( AP: Matt Dunham )

The UN's intervention will have no impact on the court proceedings already underway, but Ecuador could be found to have breached international law.

"The case is important because it concerns a very special set of circumstances where a person who is not formally under detention yet was subjected to surveillance," Professor Cannataci said.

"What we have to establish is the surveillance based on a measure, one which is provided for by law and secondly is it a measure that is both proportionate and necessary to the circumstances of the case."

Assange is next due to appear before court via video link on May 2, in relation to a US extradition request over allegations he conspired with former military analyst Chelsea Manning to download and disseminate classified material.

That appearance will be a short mention, with US prosecutors expected to issue a more detailed argument for extradition in June that could include further charges.

The Swedish prosecutors' office is also considering a request to reopen a rape investigation involving Assange that was closed in 2017.

Professor Cannataci said he had also received a preliminary assessment of a case filed on behalf of Ecuadorian President Lenin Moreno, who accused Assange of breaching his asylum conditions before his expulsion.