An Irish drug dealer who earned millions of euros in cryptocurrency has lost his fortune after the access codes to his riches were destroyed.

Clifton Collins' 12 Bitcoin accounts had a total of €53.6 million (NZ$91.5 million) inside them, but his money may never be accessed because of the missing codes.

In early 2017, Collins, 49, had a dilemma of where to hide the Bitcoin codes to his illicit fortune. He came up with the idea to print them on an A4 piece of paper and hide it in the cap of a fishing rod case in his rented home in Cornamona, County Galway, the Irish Times reports.

But soon after, police arrested Collins when they found €2000 (NZ$3417) worth of cannabis in his car and he was sentenced to five years in jail. There was also a break-in at his rental home and his possessions were cleared on his behalf by the landlord and taken to a dump.

Among what was disposed of from the house were the Bitcoin codes, meaning the accounts can't be accessed.

Workers at the dump told police they remember seeing disposed fishing gear, but waste is sent to Germany and China to be incinerated and the fishing rod case was never found.

Collins has told police he has had time to come to terms with the loss of the money and considers it a punishment for his own stupidity.

According to the Irish Independent, he has forfeited all his Bitcoin because it is proceeds from crime.

Collins bought most of the Bitcoin in 2011 and 2012 using money he'd earned from growing cannabis.

The cryptocurrency's value has since risen and in early 2017 he had just over 6000 Bitcoin in one account.

He feared a hacker may easily steal it so he spread his fortune across 12 accounts, each with 500 Bitcoin (NZ$7.6 million) inside them.

Although the Irish Criminal Assets Bureau has confiscated his accounts and they can't get the money, they're hopeful advances in technology will one day allow them to access the Bitcoin so it can be sold.