Ecuadorian authorities on Monday carried out an inventory of the belongings and devices left at the London embassy following his expulsion from the diplomatic compound that had been his home the past seven years.

It came as Sweden announced it was seeking Assange's arrest on suspicion of rape, setting up a possible tug-of-war with the United States over any extradition of Assange from Britain.

It's not known what devices authorities removed from the embassy or what information they contained.

However authorities said they were acting on a request by US prosecutors, leading Assange's defenders to claim Ecuador has undermined the principles of asylum while denying the secret-spiller's right to prepare his defence.

"It's disgraceful," WikiLeaks' editor in chief, Kristinn Hrafnsson, said.

"Ecuador granted him asylum because of the threat of extradition to the US and now the same country, under new leadership, is actively collaborating with a criminal investigation against him."

Assange, 47, was arrested on April 11 after being handed over to British authorities by Ecuador.

He is serving a 50-week sentence in a London prison for skipping bail while the US seeks his extradition for conspiring to hack into military computers and spill secrets about US operations in Iraq and Afghanistan.

Hrafnsson, who has visited the Australian in jail, said Assange saw his eviction coming for weeks as relations with President Lenin Moreno's government deteriorated.

He said he he took great care to scrub computers and hard drives of any compromising material, including future planned leaks or internal communications with WikiLeaks collaborators.

Still, Hrafnsson said he fully expects Moreno or the Americans to claim revelations that don't exist.

He called Monday's proceedings a "horse show" because no legal authority can guarantee Assange's devices haven't been tampered with, or the chain of custody unbroken, in the six weeks since his arrest.

"If anything surfaces, I can assure you it would've been planted," he said.

"Julian isn't a novice when it comes to security and securing his information. We expected this to happen and protections have been in place for a very long time."

A group of Assange's supporters gathered outside Ecuador's Embassy in London to protest the judicial proceeding.

Demonstrators put banners on the railings with images of Assange, his mouth covered by an American flag, and chanted "Thieves! Thieves! Thieves! Shame on you!"

Ecuadorian authorities said they will hand over any belongings not given to US or Ecuadorian investigators to Assange's lawyers, who weren't invited to Monday's inventory-taking.

Hrafnsson said he didn't have a full inventory of Assange's devices.

Australian Associated Press