NSW Police officers have collected a poo hidden inside a book that was dumped outside Tony Abbott's Sydney electorate office.

The faeces was placed inside a hollowed out book that had the word "Unpopular" written on the cover, according to photos published by News Corp Australia.

Detectives are investigating after the item was left outside Mr Abbott's Manly office on Tuesday morning, a police spokesman told AAP.

"Police attended and the item has been collected," he said.

The former prime minister's office has been contacted for comment.

Police also appealed for information late last week after posters featuring Mr Abbott appeared in his Warringah electorate with expletives written across his forehead.

Other posters had "Pell" written across them - an apparent reference to the Liberal MP's friend and convicted pedophile Cardinal George Pell.