The items were apparently found during a search of a burial ground in Edmonton.
Earlier, Sky News reported that a man who had admitted taking part in the raid wrote to Sky offering to reveal the whereabouts of the stolen goods.
He was escorted from prison to the cemetery to show officers where to dig.
The contents of 72 safety deposit boxes were taken during the heist in April.
Jewellery, cash and other items valued at up to Â£20m were taken in the burglary over the Easter Bank Holiday weekend. The BBC has learned that "many millions" are still missing.
Sky News said its crime correspondent was contacted by Danny Jones, 58, one of four men who had pleaded guilty to conspiracy to rob the Hatton Garden vault over the Easter weekend.
Five others pleaded not guilty and are due to stand trial next month.
Police investigating the Hatton Garden jewellery raid have recovered what is believed to be some of the stolen property at a north London cemetery.