The winners - who nicknamed themselves the "Lucky 13" when they started their syndicate at a tool manufacturing company in Columbus, Ohio - won big on odds of 80-million-to-one.

Correspondent Stephen Sackur: "The statistics are mind-boggling."

They each now stand to get about £12.4m.

It would have been even more, but they decided to take a one-off cheque instead of payment in instalments totalling $295m over 25 years.

The winning ticket is being kept in a safe deposit box until it is sent by armoured car to Indiana for verification.

'We are really getting nervous'

So far only one of the overnight millionaires has shed his anonymity to speak to the media.

John Jarrell said he and his fellow-winners were one "big happy family" and were nervous about their sudden fame.

"We are really getting nervous and scared about what we got to do with all of this," he said.

"We are ready to go shopping and get on with normal life as soon as all you people leave us alone."

Learning to say no

The winners have hired lawyer Larry Sturtz to represent their interests.

Larry Sturtz: Cautious advice

He said his new clients were in "a state of shock"; adding: "They're trying to figure out what to do with their lives."

Mr Sturtz said he warned them about securing good investment advice and avoiding the pitfalls of many who fritter away huge windfalls. His message to them was to "learn how to say no."

Larry Sturtz explains how to hang onto your windfall

There are already signs that the syndicate winners will not let the money go to their heads. Barb Palmer, the accounting manager at the 170-worker factory where the machinists work, told reporters that nine of the 13 had said they planned to keep their jobs.

"We hope we don't lose any of them. This is a great team spirit organisation," he added.

Lottery madness

Powerball began as an attempt by a group of smaller US states to compete with fundraising lotteries held in large states.

Correspondent Richard Lister on the "Ticket-buying frenzy"

Its popularity rocketed, and this week the excitement reached fever-pitch when the jackpot was pushed to new heights after no winner emerged from the draw on Saturday.

More than 210m tickets were sold in the four days leading up to the draw on Wednesday.