The Attorney General has vetoed the disclosure of letters written by the Prince of Wales to ministers.

Dominic Grieve said that the correspondence between Charles and seven Government departments was part of his "preparation for kingship".

Making the letters public could potentially damage the principle of the heir to the throne being politically neutral, and so undermine his ability to fulfil his duties when king, said Mr Grieve.

The Government had been ordered to disclose the letters sent during a seven-month period in 2004 and 2005 by Charles, after a journalist won a freedom of information appeal.