Former chancellor George Osborne has called in police to investigate alleged online harassment after a so-called “poison pen” email was sent to guests due to attend his wedding this weekend.

Friends say the email – which has since been posted online – is part of a “long-term campaign” of abuse in which an individual has “made up rumours” and engaged in “cyber bullying”.

The ex-MP and his fiancee are said to be “really upset and distressed” by the situation.

Mr Osborne is due to marry his former Treasury adviser Thea Rogers in a ceremony in the Somerset town of Bruton on Saturday afternoon.

It is understood the couple believe they know the identity of the person behind the email – which was sent to several politicians and journalists on Thursday afternoon.

The individual is not thought to be directly connected to Mr Osborne, and their specific motivation is also unclear.

Police are said to be investigating the case, with legal action also ongoing.