The King's brother Andrew Mountbatten-Windsor released under investigation after arrest

The King's brother, Andrew Mountbatten-Windsor, has been released under investigation following his arrest on Thursday.

Thames Valley Police had kept him in police custody while his properties were searched.

Andrew Mountbatten-Windsor is suspected of an offence called 'misconduct in public office'.

BBC Correspondent Dominic Casciani explains that is "an allegation that someone who was doing a job on behalf of the British public did something seriously wrong, knowing it to be wrong".

In this case, he is suspected of sharing confidential government and financial information with a convicted criminal.

In a statement, King Charles said the "law must take its course" and that the police had his "full and wholehearted support and co-operation".

Being released under investigation does not rule out further questioning at a later date.

At some point a decision will have to be made about whether to charge the King's brother with misconduct in a public office.

BBC Royal correspondent Sean Coughlan says Andrew Mountbatten-Windsor is the first senior member of the Royal Family to have been arrested in modern history.

Andrew Mountbatten-Windsor has previously always denied doing anything wrong.