Visitors are being told to stay out of the sea at Portstewart Strand while officials investigate a water pollution incident.

The advice was posted by the National Trust, which manages the beach, on Wednesday morning after the Department of Agriculture, Environment and Rural Affairs was alerted the previous evening at 20:18 BST. Daera issued a temporary advice against bathing notice as a precaution while tests are carried out.

The Northern Ireland Environment Agency’s pollution response team and Daera marine staff have been on site collecting samples. A National Trust spokesperson said one line of inquiry is that food waste or grease may have entered the sea via the River Bann, but the cause has not been confirmed.

Visitors are asked to keep dogs on a short lead and not let them enter the water. Swimming is not recommended until further notice.

A Daera spokesperson said the measure is intended to protect public health while information is being gathered. Initial water sample results are expected on Thursday morning and the notice will remain in place while testing and investigations continue.