Kate Middleton
Kate Middleton allegedly believes that there is a spy in the palace who is tracking her every move.AFP / Getty Images

Kate Middleton reportedly believes that there is a spy in the palace who is tracking her every move.

According to Life & Style Magazine, the Duchess of Cambridge and Prince William are trying to find out who has been leaking their secrets to the press.

"She's paranoid that someone inside the palace is leaking her secrets. It's her worst nightmare," an insider said.

"They're trying desperately to find out who's spying on them by giving out false information to different people. If any of that information comes out, they'll know who's responsible," the source added.

It was previously reported that the royal couple have accused the press of intruding into Prince George's life and have threatened legal action.

"Kate and William have vowed to do everything in their power to protect George. They will not rest until they find the spy," the source continued.

The 32-year-old royal, who is pregnant with her second child, has been suffering from hyperemesis gravidarum, a potentially serious pregnancy illness causing vomiting and a bodily reaction to the intake of food and liquids.

To regain her health, Middleton has returned to her family home in Bucklebury, Berkshire, with Prince George.

Meanwhile, on 21 October, the Duchess and Prince William will welcome Singaporean President Tony Tan to Britain, Buckingham Palace has confirmed.