It was originally thought the value of the items stolen over the 2015 Easter holiday was £14m.
But Woolwich Crown Court heard prosecutors are now seeking the larger sum from the five "ringleaders" convicted of the robbery.
If they do not pay back the sum they face a maximum of 14 years being added to their sentences without parole.
The court heard the full confiscation hearing - set to begin in January 2018 - is expected to last around six weeks.
The Hatton Garden raid over the Easter Bank Holiday weekend of 2015 was already Britain's biggest ever burglary.
The gang raided safe deposit boxes for jewels after boring into the vault of the now defunct Hatton Garden Safe Deposit Ltd.
An estimated two thirds of the valuables remain unrecovered.
In June 2016 - after the trial - a woman came forward reportedly alleging that she had lost £7m worth of gold in the raid.
John "Kenny" Collins, 76, of Islington; Daniel Jones, 62 and Terry Perkins, 68, of Enfield; and the group's oldest member, Brian Reader, 78, of Dartford, Kent, pleaded guilty to conspiracy to commit burglary last year.
Collins, Jones and Perkins were each given a seven-year prison term for their involvement in the burglary.
Reader, who was too ill to attend the initial trial, was later given a six years and three months sentence.
Carl Wood, 59, and William Lincoln, 60, were sentenced for the same offence and one count of and conspiracy to conceal, convert or transfer criminal property, after a trial.
The two men were given six and seven-year sentences respectively.
The value of the goods stolen in the Hatton Garden jewellery raid has risen to an estimated £25m.