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 recent multi-million pound heist in London's Hatton Garden may be linked to a major electrical fire in nearby Holborn the previous week, a former senior police officer has claimed.
John O'Connor, once head of Scotland Yard's elite Flying Squad, made the remarkable claim in an interview with LBC, as he said he believed the fire "probably was deliberate".
The blaze, which began in Kingsway, Holborn on Wednesday, was not extinguished until late on Thursday and led to widespread outages and road closures in the area in the following days.
He said police would likely be investigating links between the two incidents because "that seems to me to be too much of a coincidence".
He also suggested that one line of inquiry would be whether the robbers had "insider information" to help them with the audacious raid.
O'Connor added that the stolen diamonds were likely to be sent abroad, telling the station: "If I was a betting man, I'd put a bet on that they will arrest a handful of people involved in the actual obtaining of the diamonds. I doubt if they'll get the diamonds back."
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.