Buckingham Palace is investigating following reports a member of staff was arrested after a Christmas party.
The incident is said to have occurred at a branch of All Bar One in central London following a drinks reception at the royal residence.
The Metropolitan Police said officers were called to a bar in Victoria shortly after 9pm on Tuesday after reports a customer had smashed glasses and tried to assault a member of staff.
A 24-year-old woman, who The Sun reported is believed to work as a maid at the palace, was arrested on suspicion of assault, criminal damage and being drunk and disorderly.
A witness told the newspaper: “The group walked in and this one girl just got hysterical.
“She started smashing glasses and abusing our staff members, so we had to call the police.
“I’ve never seen one person get that crazy during a night out. She was on another level.”
Police said the woman was taken into custody and released the following evening after being handed a fine for disorder.
A palace spokesperson said an investigation has been launched into the incident.
“We are aware of an incident outside the workplace involving a number of household staff who had previously attended an early evening reception at the palace,” they said.
“While this was an informal social gathering, not an official palace Christmas party, the facts will be fully investigated, with a robust disciplinary process followed in relation to individual staff and appropriate action taken.”
Around 50 staff members were said to have been at the bar after they had earlier enjoyed drinks at the palace.
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The Met said: “Officers were called to a bar in Victoria Street, SW1 following reports that a customer had smashed glasses and attempted to assault a member of staff.
“Officers attended and arrested a 24-year-old woman on suspicion of common assault, criminal damage and being drunk and disorderly.
“She was taken into custody and released the following evening having been given a penalty notice for disorder.”