Despite the bold claim, the Tesla billionaire struck a somewhat measured tone, tweeting to his millions of followers on Friday: "Cryptocurrency is promising, but please invest with caution!" Musk's tweet linked to a video from celebrity news website TMZ, in which he warned: "First of all, I think people should not invest their life savings in cryptocurrency. To be clear, I think that's unwise."

Yet Musk added: "If you want to sort of speculate and, I don't know, maybe have some fun, I mean, there's a good chance that crypto is the future currency of earth." Asked about dogecoin, Musk said: "The point is that dogecoin was invented as a joke, essentially to make fun of cryptocurrency."

He added: "Fate loves irony… What would be the most ironic outcome? That the currency that was invented as a joke in fact becomes the real currency." Yet Musk admitted there were problems with dogecoin - the meme asset that has rallied more than 25,000% over the last year to become the fourth-biggest cryptocurrency. Asked whether dogecoin's unlimited supply poses a danger to its price compared to bitcoin, which has a fixed supply, Musk said: "Yes, it does."

But he later repeated the mantra of dogecoin investors: "To the moon!" Musk, the co-founder and chief executive of electric car company Tesla and the world's second-richest person, has been right at the centre of the 2021's wild boom in cryptocurrencies. Tesla's announcement in February it had bought $1.5 billion of bitcoin laid the foundations for a monster rally in the world's most famous crypto asset. And his frequent tweets about dogecoin have been perhaps the main driver of the buzz around the meme token. Analysts said the recent breakneck rally in dogecoin had come in part because of people trying to get in before Musk appeared on Saturday Night Live on May 8, where many predict he will riff on cryptocurrencies.