The trial of 12 men accused over a Paris heist in which reality TV star Kim Kardashian was robbed of millions of dollars' worth of jewellery appeared one step closer after prosecutors asked for the case go to court, a source told AFP.

Five members of the gang stormed the luxury residence where Kardashian was staying during Paris Fashion Week in 2016, holding the star at gunpoint and making off with a huge diamond ring and other gems worth a total of nine million euros ($9.5 million).

Prosecutors will seek to take the case to court for all 12 - who are currently at liberty but under legal supervision - charging them with armed robbery, kidnapping and criminal association, a judicial source said Wednesday.

Examining magistrates must now decide whether the case will proceed to trial, the source added, although any trial is not expected to begin until 2021.

Wearing police uniforms, the gang burst into Kardashian's apartment, gagged and bound her and locked her in a bathroom before helping themselves to gems including a 20-carat Lorraine Schwartz diamond ring worth some four million euros.

One of the alleged robbers, Yunis Abbas, fleeing the scene on a bicycle, dropped a diamond-encrusted cross worth 30,000 euros, which was found by a passer-by a few hours later.

It remains the only piece to be recovered from the brazen heist, the biggest jewellery theft from an individual that France has seen in more than 20 years.

The alleged mastermind, Aomar Ait Khedache was arrested after his DNA was found at the site. 

He told investigators he had struggled to find a buyer for the Lorraine Schwartz ring, complaining it was "too recognisable" and that he had given it to an unidentified third party.