A royal chauffeur has been suspended pending an investigation into claims he allowed two undercover News of the World reporters into Buckingham Palace in exchange for money.
The paper's investigations editor Mazher Mahmood reported on Sunday that chauffeur Brian Sirjusingh was paid £1,000 by reporters in exchange for access to the building.
The pair posed as wealthy Middle-Eastern businessmen and were allowed into the building without security checks.
Once inside, he showed them several vehicles used by members of the royal family and allowed one reporter to sit in a Bentley used to transport the Queen on state occasions.
It was also reported that Sirjusingh revealed codenames used by royal protection officers for two of the cars used to transport the Queen and told them about her travel plans.
Strict security measures are meant to be in force at the palace and even members of the royal family, including the Duke of Edinburgh and the Prince of Wales, are required to show photographic ID each time they enter a royal residence.
A Scotland Yard spokesman said: "We are naturally concerned about the issues raised by this story and are liaising with palace officials about their staff security arrangements."
This is not the first time security has been breached at the palace. Daily Mirror journalist Ryan Parry managed to get a job as a footman in 2003.
In a comment piece published alongside its undercover report, the News of the World said: "Our expose of Buckingham Palace security is breathtaking.
"How many more times must the uninvited gain access, and how many more botched reviews must there be, before we are confronted with a tragedy of monumental propotions?"
A former head of the royal protection squad, ex-chief superintendent Dai Davies, said royal security needed to be shaken up.
"We need to look at the whole way we do this. This has exposed yet again weaknesses in security and the fact they have failed to learn from history," he said.
"It beggars belief they can take people in there without having to show photographic ID and vouch for them. That should be a secure, controlled zone.
"Many of the royal staff are not paid very much and some may well be tempted by something like this. I'm incredulous about the whole thing."