Kristinn Hrafnsson, editor in chief of Wikileaks, talks to the media outside the Westminster Magistrates Court on Thursday. Hannah McKay / Reuters

A collaborator of WikiLeaks founder Julian Assange was arrested on Thursday in Ecuador while trying to flee to Japan, the South American country's interior minister said.

Maria Paula Romo did not identify the person but told Sonorama radio he was very close to Assange, who was arrested on Thursday in London on a US extradition request after spending seven years in the Ecuadoran embassy there.

Channel Teleamazonas identified him as Ola Bini, a software developer focused on privacy, security and cryptography, but did not name its source.

Earlier on Thursday, the minister had linked the collaborator with alleged attempts to destabilise the government of President Lenin Moreno.

He "has been detained simply for investigation purposes," she said, adding he had taken foreign trips with former Ecuadoran foreign minister Ricardo Patino, who gave political asylum to Assange in 2012.

"We have sufficient evidence that he was collaborating in attempts to destabilise the government," she said.

Romo's announcement followed the arrest of Assange earlier on Thursday.

British police moved in after Ecuador pulled its asylum for Assange and cancelled his citizenship, granted in 2012.

He had been living in the embassy, fearing arrest, but the Ecuadoran government says that Assange "repeatedly violated" the conditions of his protection.

The US Justice Department said Assange was being charged with a computer hacking conspiracy relating to his work with former US intelligence analyst Chelsea Manning in March 2010.

Agence France-Presse