The Virgin boss was supposed to be apologising for delays on his train services, but ended up apologising for his language instead.
The slip came during an interview with Andrew Neil on BBC Radio 5's breakfast programme, as he tried to smooth over the furore caused by lengthy delays on Virgin's West Coast trains to Blackpool last weekend.
Virgin was faced with a stream of angry MPs, delegates and journalists demanding compensation after journeys were disrupted on their way to the Labour Party conference.
Mr Branson began a lengthy explanation about engineering works and old rolling stock, but then reverted to a rather more succinct version of events, saying: "We f***ed up, we f***ed up badly on that day."
The embarrassed tycoon quickly changed this to "screwed up" after a heavy prompt from Andrew Neil and later apologised profusely for his language, saying: "I am extremely sorry, it just came out!"
Mr Neil went on to challenge Mr Branson over reports of bad food, dirty trains and long delays, asking why people couldn't expect the same standard of service on his trains as on his airline.
Last Sunday, the Health Secretary, Frank Dobson, had to wait at Euston for almost an hour because the train he and other delegates intended to catch had no driver.
A number of other ministers using Virgin Trains also experienced delays, including Baroness Jay, Leader of the Lords, Tessa Jowell, the Health minister, and Patricia Hewitt, the Economic Secretary to the Treasury.Reuse content