Letters warning against 'acts of harassment' of the Duke and Duchess of Cambridge at their Norfolk home have been distributed by police.

Kate and William left London for Anmer Hall, on the Queen's private Sandringham estate, with their new baby Princess Charlotte and her elder brother Prince George yesterday.

The BBC said letters had been given to media by Norfolk Police stating that while the Cambridges are in residence they have 'a more than reasonable expectation of privacy'.

The letter, undersigned by the couple's communications secretary, called for 'acts of harassment and breaches of privacy to cease'.

It said: 'There have in the past been a number of intrusions into the privacy of the Royal Family which in the main have been as a result of professional photographers using long-distance lenses, not only to observe the Royal Family, but also to photograph them going about their activities on the estate.'

Previous warnings to photographers meant 'the position has greatly improved'.

But it continued: 'However, we would remind you again of the position. The Sandringham Estate trusts that there will not be a need to take any further action other than bringing these points to your attention.'

A spokeswoman for Norfolk Police confirmed officers had been handing out the letters on behalf of Kensington Palace.

In the past the letters have been routinely given to individuals who unintentionally or otherwise find themselves on or near private land at Anmer.

A Kensington Palace spokeswoman said: 'The warm-hearted and understandable interest in the Royal Family and the Duke and Duchess of Cambridge needs to be balanced with their right to private family life - this is especially important for a family with very young children.

'This is a letter given by police to individuals found operating on or around the Sandringham estate, including Anmer, on behalf of the royal household.

'It reminds them of their responsibilities and the rights of the estate. Media are encouraged to speak to royal communications for further guidance about where they can operate on this private estate.'