An Italian couple have been arrested for allegedly sending thousands of threatening letters, often including soiled toilet paper, to public figures.

The strange scheme had been going on for two years before the Milan branch of Italy’s anti-terrorism squad, Digos, arrested the pair on Wednesday over accusations of threats and defamation. A 71-year-old former police officer and his 51-year-old partner were allegedly targeting high-profile people they accused of corruption, paedophilia or murder.

"The man followed the news closely and was very up-to-date on things," Digos officer Carmine Mele told Italian news agency Ansa. "He had sent the letters practically everywhere."

The unpleasant post was sent to a range of people involved in sports, business, politics and TV.

This included the directors of Copenhagen Zoo after the death of a giraffe there, teachers accused of child abuse, football club and politicians who had earned the pair's displeasure, according to Ansa.

In the envelopes, the recipients would find a threatening message often accompanied by toilet paper stained with the couple's pet dog's excrements.

A notebook was found at their address with a list of people intended to receive a parcel and the reason for targeting them, along with 110 letters ready to be sent.