Shopkeepers are on the look out for a person who defecated twice near their front doors.

The mystery first emerged last week when Alan Buckley, owner of Clever Buys in Finglas, north Dublin arrived to open up and saw and smelled human faeces on the footpath.

After talking to neighbouring businessmen he checked CCTV to discover the incident had unfolded in the middle of the night.

"I haven't a clue why anyone would do this," he said.

The first incident occurred on September 15 and a repeat offence happened on Wednesday of this week about 10 feet from the front door of his shop.

"There was a load of toilet roll on the ground," Mr Buckley said.

"I couldn't understand it. There's no-one wipes their dog's arse. And it was humongous. And the smell of it. It nearly made me sick."

Mr Buckley said his security camera recorded a car pulling up in front of the row of shops before dawn on each occasion and a person getting out and opening the boot and spending a short time at the rear of the vehicle.

"I wouldn't mind but we're the cheapest around for toilet roll. We do 40 rolls of toilet paper for a tenner. We're famous for toilet rolls," he said.

Insisting he has not fallen out with any customers, Mr Buckley tried to make fun out of the incident by borrowing a toilet from a plumbers and piling up some of his stock of toilet rolls on the footpath beside his shop with the message: "We go that extra mile for our customers. Other shops couldn't give a shit."