Howells tweeted this picture shortly after discovering he accidentally threw away 7500 bitcoin.

Howells tweeted this picture shortly after realising he accidentally threw away 7500 bitcoin.

A British IT worker has launched a frantic search of a landfill site after realising he accidentally threw away a computer drive holding $7.9 million in the online currency bitcoin.

James Howells, 28, obtained 7500 bitcoins in 2009 when the currency was virtually worthless. Its value has since soared, with a single bitcoin hitting $US1000 ($1101) for the first time last week.

Howells left the hard drive in a drawer for several years, and threw it away earlier this year without a second thought.

Bitcoin: The future of currency?

Bitcoin: A man accidentally threw out $7.9 million worth of bitcoin. Photo: Reuters

To his horror, he then realised what it had contained - and that he would be a millionaire, if he could only find it.

He now faces the prospect of a painstaking hunt through a massive landfill site in his home city of Newport, Wales, he told BBC television.

"When I went to the tip the manager took me up to the current landfill site and when I saw it — it's about the size of a football field — my first thought was 'no chance'," he said.

James Howells.

James Howells. Photo: ABC TV/BBC

"The manager explained that things that were sent to landfill three or four months ago could be three to five feet (1.5 metres) deep.

"He confirmed my worst fears when he said that."

Large-scale searches of the landfill site — including those for police evidence — usually involve up to 20 workers with digging equipment and dogs, he added.

"The truth is, I haven't got the funds or ability to make that happen at the moment without a definite pay cheque at the end of it," Howells said.

He told the BBC he forgot about the bitcoin stash because he was "distracted by family life and moving house".

The hard drive was thrown out between mid-June and August, he believes.

He has checked all of his back-up files without success.

Launched in 2009 as the invention of a mysterious computer guru who goes by the pseudonym Satoshi Nakamoto, bitcoins can be exchanged online for real money or used to buy goods and services on the internet.

The currency is not regulated by any government.

AFP