Police have released CCTV images of a van and three suspects wanted in connection with the Hatton Garden Safety Deposit raid.
Scotland Yard said the trio were "highly audacious" and entered the building in London's jewellery quarter twice over the Easter weekend.
The images have been released by police after CCTV footage apparently showing a gang of burglars carrying out the raid was published by the Daily Mirror.
The Metropolitan Police have said "nothing in the investigation so far" indicates a link between the Holborn electrical fire and a multi-million pound heist at Hatton Garden less than a week later, but added that "all lines of enquiry are open".
Separately, London Fire Brigade said that their initial assessment suggests the fire was caused by an electrical fault in the tunnels running underneath the Kingsway.
Detectives offer £20,000 reward for information leading to the arrest and conviction of the Hatton Garden burglars.
A Ukip candidate believes he may have lost valuables in the Hatton Garden raid in London.
Police have released CCTV images of a van and three suspects wanted in connection with the Hatton Garden Safety Deposit raid in London.