Dog owners have been warned to keep their pets on leads after an “orange liquid” substance appeared along the waterline in West Mersea and Clacton.

The Environment Agency was called on Wednesday morning to reports of the mystery liquid and is carrying out tests to discover what it is.

Colchester Borough Council is also aware of the substance, warning dog walkers to keep their animals away from the water’s edge.

A spokesman for the Environment Agency said: “We received an initial report from a member of the public at 9.10am reporting that an orange liquid was washing onto the beach at West Mersea, and that there was a lot of debris associated with this.”

The liquid was said to be in “long strips along the beach”, stretching for several hundred metres in either direction from Seaview Avenue.

Environment Agency officers were sent to the scene to try and identify the substance.

“We have also been liaising with Colchester Borough Council who would normally lead on any shoreline clean-up of public beaches, should it be required,” the spokesman said.

“We have since received similar reports from members of the public in Clacton and we are liaising with Tendring District Council at that location.

“Samples taken at West Mersea today will be analysed by our experts, working with CEFAS.

“No signs of any dead or distressed wildlife have been found and initial observations suggest this may be the result of a natural event.”