An Auckland aquatic centre's main pool was closed today after several teenage water polo players fell ill and were taken to hospital.
The players became unwell after taking part in the northern region under-14 division one boys' finals at the West Wave Aquatic Centre in Henderson yesterday.
The
venue is due to host the national swimming championships, beginning tomorrow.
The water polo tournament involved eight teams -- six from Auckland, and one each from Hamilton and Tauranga.
A New Zealand Water Polo official said up to 10 players were taken to hospital with respiratory problems, six in Auckland and the rest in Hamilton.
Most had been discharged, with the rest expected to go home by the end of the day.
Waitakere City Council spokesman Dai Bindoff said the council was deeply concerned by what had occurred and investigations were continuing into the cause, which remained a mystery.
He said the water was of a high quality, and the levels of treatment were normal and well within national guidelines.
There had been nothing similar at the pool in the past and he described the incident as "completely freak".
"We are still struggling to understand what has happened here," he said.
"We have had people working on possible explanations since yesterday, but so far have not come to any definite conclusions."
Other pools in the complex were not affected.
The council hoped the main pool could be reopened tomorrow, but that would depend on what testing uncovered over the course of today.
"We've got thousands of users every day so we've not taken this decision lightly," he said of the closure.
"But when you've got kids getting sick, you have to do something."
Auckland water polo association chairman Chris Haywood said players began complaining of breathing difficulties yesterday morning.
Just after lunchtime, two or three of them began feeling ill and a decision was made to switch matches to a different pool in the complex.
"Obviously we are concerned that the health of some of our players was compromised," he said.
"We are working with the council to ensure that everything that needs to be done is done."
- NZPA
