Updated

Ecuador's government said Wednesday that a microphone found in its London embassy, where Wikileaks founder Julian Assange is staying, was hidden inside an electrical outlet in the office of the ambassador.

Foreign Minister Ricardo Patino told a news conference in Quito that the bug was found in mid-June when Ecuadorean technicians reviewed the embassy's wiring.

The purpose of the hidden microphone was to listen to the conversations of Ambassador Ana Alban in her office, Patino said, holding up a picture of the purported bug. Assange lives and works in a different room in the embassy.

"We have reason to believe that the bugging was carried out by The Surveillance Group Limited, one of the largest private investigation and covert surveillance companies in the United Kingdom," he said.

The foreign minister said Ecuador was going to ask for the cooperation of Britain's government in investigating the alleged bugging.

The system worked with a SIM card and could be activated by a call from any cellular of fixed-line phone, he said.

Assange was granted asylum by Ecuador last year. He has been living inside the South American country's embassy in London to avoid extradition to Sweden to face allegations by two women of sexual assault, which he denies. Britain will not give him safe passage if he leaves the embassy.

Assange believes extradition to Sweden is merely a first step in efforts to remove him to the U.S., where he has infuriated officials by publishing secret documents including 250,000 State Department cables.