The grim news comes hot on the heels of similar revelations that a British Airways flight from Heathrow to Dubai was forced to turn back 30 minutes into a seven-hour flight after passengers were overwhelmed by the nauseating and all-pervading whiff of a terror poo in the one of the toilets.

The latest ‘poodunnit’ surrounds a mystery pool pooper who has struck on five successive Friday evenings – at least they’re regular – at the Splash Palace swimming centre at Invercargill, on South Island.

Bosses are keen to flush out the culprit, who has cost the pool tens of thousands of dollars in lost revenue. Each poo discovery triggers a ‘code brown’ alert, meaning the pool has to be evacuated immediately, and then closed for six hours to be cleaned.

City aquatic services manager Pete Thompson said the serial arse-nist generally struck after 5pm on Friday evenings. It is unclear whether more than one culprit is involved – the discovery of deadly Richard IIIs in three pools on the same night on one occasion has further muddied the waters.

“They did one in the leisure pool and we moved the kids to the learners’ pool, and they did one in the learners’ pool and we moved the kids to the main pool, and one appeared in the main pool, so we had to shut the whole thing down,” said Mr Thompson, as reported in The Southland Times. “In one of the pools was diarrhoea….that was unfortunate.”

Mr Thompson said the incidents appeared to be deliberate, but signs have now gone up warning people not to swim if they have upset stomachs. He insists he is closing in on the pooper, but the council will have to prove the person acted deliberately in order to claim cleaning costs.

“There are certain sports groups which use the facility at that time of the day,” said Mr Thompson. “If we do manage to – dare I say – catch someone in the act, we will seek compensation.”