Prosecutors say the cash was hidden in the shed

Tax officials say the sisters hid almost 6bn yen (£29m; $58m) in cardboard boxes and paper bags at their home in the city of Osaka.

They are accused of failing to declare most of the money they inherited from their wealthy father, who died almost four years ago.

The National Tax Agency say it is the biggest ever case of its kind in Japan.

Prosecutors say Hatsue Shimizu and Yoshiko Ishii inherited about 7.5bn yen when their father, who owned a property and finance company, died in 2004.

Cash in the shed

However they declared a fraction of that amount to the authorities, allegedly stashing the rest away, and thereby avoiding 2.86bn yen in inheritance tax.

Prosecutors and officials from the Osaka taxation bureau raided 10 locations in connection with the case, including Hatsue Shimizu's home.

A tax official said they had concealed most of the money in cash in a shed attached to the house.

"We have confiscated 50 cardboard boxes," he said.

Hatsue Shimizu has denied the cash was part of her inheritance, saying she had earned it herself.