The inclusion of two sex hotline numbers in The Last of Us was an honest mistake, says Naughty Dog.

The sex lines were discovered by a Kotaku reader, who saw phone numbers on a flyer in the game under the heading of “Pest control” and decided to give them a call.

The numbers were mistakenly added to the game by an artist, said creative director Neil Druckmann.

"What happened was, they put some phone numbers in the game and then they thought they could just change the area code to 555, then it's invalid because it's what they do in movies.

“But I guess that doesn't work when you have a 1-800 in front of it.

"We're now working to take it out," he added.

"It was just an honest mistake."