A man has been arrested for allegedly trespassing in the grounds of Windsor Castle.

The Metropolitan Police and Thames Valley Police have both launched investigations after the intruder was found on the grounds of the royal residence over the weekend.

A Metropolitan Police spokesperson said in a statement: "A man in his 30s has been arrested on suspicion of trespass on a protected site and possession of Class A drugs after entering restricted grounds at Windsor Castle.

"Officers in the grounds spotted the man just after 13.00hrs on Sunday, 1 June and quickly arrested him.

"He was then passed into the custody of Thames Valley Police."

It's been confirmed that the man was "quickly challenged by Met police officers and arrested" after he gained access to the grounds of the castle.

Thames Valley Police said: "At just after 1pm on Sunday 1 June a man entered restricted grounds at Windsor Castle.

"He was quickly challenged by Met police officers and arrested. He did not enter the inner grounds of Windsor Castle.

"He was arrested on suspicion of trespass on a secure site and possession of class A drugs. He has been bailed and an investigation is ongoing by Thames Valley Police."

The Duke and Duchess of Cambridge live in Adelaide Cottage, which is located on the Windsor estate. However, no members of the royal family were in the castle at the time of the incident, according to Sky News.

There was another security scare at Windsor Castle in October, when two masked raiders broke into farm buildings on the estate.

In a statement given to People, Thames Valley Police said at the time: "At around 11.45pm on Sunday October 13, we received a report of burglary at a property on Crown Estate land near to the A308 in Windsor. Offenders entered a farm building and made off with a black Isuzu pick-up and a red quad bike. They then made off towards the Old Windsor/Datchet area.

"No arrests have been made at this stage and an investigation is ongoing."