Sir Richard Branson has called for another vote on Brexit, warning that the UK is "dangerously close to full-scale disaster".
Despite the EU having granted an extension to the Brexit deadline, in a blog on the Virgin website, the entrepreneur claimed Prime Minister Theresa May was no longer acting in the national interest, and called for the public to have "a final say".
The blog comes a day after an estimated one million people marched in London calling for a 'People's Vote'.
Sir Richard, who lives in the British Virgin Islands, said: "At this juncture, it seems implausible that another motion to vote on the withdrawal agreement would actually win majority Parliamentary support.
"And even with an extended Brexit deadline, that's a major risk to the UK, and to the Union itself.
"This is a moment of profound national crisis for the UK."
He added: "By limiting the MPs' choice yet again to one between her own deal and no deal at all, she is placing a dangerous bet."
The businessman has been a prominent campaigner for remaining part of the EU, particularly warning that businesses would be severely affected.
In the blog post, Sir Richard added: "Nearly three years after the 2016 referendum, that evidence tells us that few, if any, of the original assumptions about leaving the EU were correct.
"Thousands of jobs in Britain have been lost already, with many more redundancies on the horizon as manufacturers react to the looming threat of tariffs and supply chain disruptions.
"More than a trillion pounds in assets are being moved to Dublin, Frankfurt, Paris, and other European cities as financial institutions begin to execute their contingency plans."