A hidden microphone was found in Ecuador's embassy in London, where Wikileaks founder Julian Assange is holed up, Ecuador's foreign minister said.

Ricardo Patino said the origin of the bug would be revealed and explanations demanded of the country involved. He did not elaborate.

The bug was found in a routine search ahead of his visit to London on June 16, he told reporters.

The microphone was found in the office of the ambassador Ana Alban.

Patino said he was not insinuating that the bug was linked to the saga surrounding fugitive US intelligence whistle-blower Edward Snowden, who has applied for asylum in Ecuador.

Snowden is wanted by the United States on charges of espionage for revealing a massive phone and Internet surveillance program.

Assange, whose organization leaked a vast trove of diplomatic cables a few years ago, has been staying in the Ecuadorean embassy in London for a year.

He faces questioning over sexual assault allegations in Sweden, and fears the Swedes will hand him over to the US.

During his visit to London, Patino met with his British counterpart William Hague but no agreement on the Assange case was reached.

Britain is refusing to grant Assange safe passage out of the embassy so he can travel to Ecuador.

AFP