From The NOTW:
Four men and one woman were arrested in two separate raids in London on Saturday morning by officers from Scotland Yard's Serious and Organised Crime Command unit, known as SO7.
Another four people, including a second woman, were arrested in further operations conducted late on Saturday and early on Sunday, police said.
Victoria Beckham - married to Manchester United and England footballer David Beckham - said she was in "absolute and total shock" at the revelations.
Scotland Yard acted after receiving information from a Sunday newspaper about an alleged plan.
The nine are being held at unnamed police stations across London, where they are being questioned about conspiracy to kidnap and theft.
At least five of those being held are understood to be Romanian or Albanian.
One of the raids was armed and in London's Docklands area, while another was on a residential premises in Morden, south London.
The News of the World said undercover reporters had infiltrated a gang of art thieves and discovered they were also planning to kidnap the former Spice Girl.
She told the newspaper: "It's clear these people were serious and that, of course, has scared the life out of me.
"It's terrifying to think that someone would want to do that to you and your children."
She said she would be talking to her security team, adding: "But if people want to do this to my family how can you be 100% sure you'll prevent it?"
News of the World managing said his reporters had become extremely close to the gang of art thieves, with one "recruited as a potential getaway driver".
He said the gang would have been happy to kidnap the couple's two young sons, three-year-old Brooklyn and baby Romeo, as well.
"The plan was to kidnap Victoria Beckham, to take with her either or both the children if perchance they were with her... to secrete them in a safe house and to demand a ransom of £5m," he said.
The paper said the gang planned to sedate Victoria with a chemical spray and hold her in a house in Brixton, south London.
Deputy editor Andy Coulson said the plans were fairly well formed.
"They knew where they were going to carry out the kidnap, they knew how, they knew when.”
Detective chief superintendent John Coles, the head of SO7, said: "We are very grateful to the News of the World for their actions in this case which have assisted in the recovery of a number of valuable items and in preventing any other offences."
Mrs Beckham was told of the plot before watching her England captain husband play at Old Trafford on Saturday afternoon.
She did not tell her husband until after the match.
It is not the first time the Beckhams have been targeted.
In January 2000 a plot emerged to snatch Mrs Beckham and her son Brooklyn while her husband was playing for England in a match at Wembley was foiled by police.
The celebrity family were moved to a safe house for 48 hours, but no arrests were made because the kidnappers never got past the planning stage, and left no written evidence.
Posh: "It's something that's really worrying, that's every parent's worst nightmare, something happening to their child. That's scary.”
AND FROM THE NEWS OF THE WORLD
"We take her to a safe house in Brixton and wait until the money is transferred to our overseas account," said Albanian immigrant Luli Azem Krifsha.
A senior member of his ‘snatch team', a thuggish Romanian named Jay Sorin, also briefed our man: "If the kids are with her, it's even better. We ask David Beckham for £5 million. It's 100 per cent he pays. But if something happens and he don't pay, Victoria is going to die."
Our main investigator's cover story was that he was an accomplished getaway driver.
We supported this with a CV that included a fake criminal record plus the name of a ‘referee' inside Manchester's Strangeways prison who would vouch for our man. That referee is also a News of the World conact who was told to expect a ‘check call' from the gang during a prison visit.
A second investigator, introduced alongside the first and with a similar checkable cover story, pretended to be a wealthy crook.
We had been told that at least one of the gang members was armed at all times. Any meeting could have ended in disaster.
"We can pull this off," he said. "Getting Victoria isn't going to be difficult. We just have to make sure we get the money, that's the hard part. I can't believe her security is so bad. I have a friend who works in a hairdresser's where Victoria has had her hair done. On that occasion she had only one minder outside the shop." The plan, it emerged, was to ambush Victoria's car as it pulled out of the drive, force entry and sedate everyone inside with a chloroform-type spray already brought in from Italy.
"Even if you don't point it at the face it still works," explained Luli, who lives in a block of flats in Battersea, south-west London.
"It takes about three seconds to work and the person will be asleep for roughly half an hour."
"We'll wait in Brixton until the ransom money is transferred to our overseas account," said Luli.
Last Tuesday afternoon we joined Luli's sidekick, Jay, and two other gang members using the names Peter and John for a drive to Sawbridgeworth in Hertfordshire.
Here the gang studied approaches to the Beckhams' mansion—part of a month-long surveillance. "We've got three seconds before she realises what's happening," said Jay.
Last week, too, a News of the World man was present when Luli and his gang held a meeting at a restaurant called Atoca in Wandsworth, south London.
It was the first time we had seen any hint of dissent in an otherwise well-oiled operation.
"I will ask Beckham for £5million, for him that's like spending a few pence on a cup of coffee," said Luli.