Bitcoin has smashed through $14,000 (£10,460) on some exchanges, less than 24 hours after surpassing $12,000, as the boom in the cryptocurrency’s price shows no sign of ending.

Sceptics who call the market a bubble were joined by a weighty authority, however . Coutts, the Queen’s bank, has declared it to be purely speculative and refuses to invest.

“Its sharp rise brought back memories of the dotcom bubble back at the turn of the century,” said Lilian Chovin, an investment strategist at the bank.

Bitcoin has risen in price from around $760 a year ago and $360 two years ago.