London (AFP) - WikiLeaks founder Julian Assange clocked up three years Friday inside the Ecuadoran embassy in London, after claiming that Swedish prosecutors cancelled a landmark meeting in his case earlier this week.

The Australian activist said a long-awaited interview with the prosecutors fell through in what he labelled a "public relations exercise", although the prosecutor's office declined to comment.

Assange, 43, sought asylum in the embassy in June 2012 to avoid extradition to Sweden, where he faces allegations by two women, one of rape and one of sexual assault, which he denies.

The former computer hacker fears extradition to Sweden could lead to him being transferred to the United States to face trial over WikiLeaks' publication of classified US military and diplomatic documents.

Prosecutors had long insisted that he travel to Sweden for questioning but in March they agreed to go to London instead.

They said they changed their stance because some of the alleged offences will reach their statute of limitations in August.

Assange condemned what he said was the last minute scrapping of Wednesday's planned interview with prosecutor Marianne Ny.

"To behave in such a way seems reckless and it is hard to imagine that it was more than a public relations exercise," he said in a statement.

According to an email seen by The Guardian newspaper, Ny said the meeting had to be cancelled because she had not received official permission from Quito to enter the embassy.

Entering the embassy meant he jumped his English bail and police have been posted outside ever since, at a growing cost to the public purse.

A group of around 20 people gathered outside the embassy on Friday in support of Assange, with banners reading: "Don't shoot the messenger", "Free Assange" and "Thank you WikiLeaks".

A couple sang Bob Dylan's song "I Shall Be Released".

"The charges were invented by the police. The accusation doesn't have any grounds," said Gaelene Lerat, 22, from Canada.

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Silvana Salazar, 39, an Ecuadoran, said: "If he's sent to America they will jail him forever because he has information that could harm the US government.

"We support the Ecuadoran government's position of helping him. They need to let him travel to my country. It's inhumane to live in these conditions."

Assange has compared living inside the embassy -- which has no garden but is in the plush Knightsbridge district, near Harrods department store -- to life on a space station.

His 15 feet by 13 feet (4.6 by 4 metre) room is divided into an office and a living area. He has a treadmill, shower, microwave and sun lamp and spends most of his day at his computer.

As Assange remained inside -- he has occasionally greeted supporters from the balcony -- WikiLeaks on Friday began publishing more than 500,000 cables and documents it claimed were from the Saudi foreign ministry, containing secret communications Riyadh's embassies worldwide.

"The Saudi cables lift the lid on a increasingly erratic and secretive dictatorship that has... become a menace to its neighbours and itself," said Assange.