Two more dead swans have been spotted on the River Great Ouse.

An investigation is continuing into the death of birds on the river between Mill Lane, Little Paxton, and St Neots Marina following the discovery of 13 dead swans and seven ducks in September.

Mick Nolan, who was walking his dog by the marina on December 3 spotted the latest dead birds. He said: “I crossed Eynesbury bridge and walked up towards town. I was walking by the side of the road when I peered into the river and saw two dead swans.

“I was shocked – it's not something I have ever seen before. You just don't expect to see it.”

A Natural England spokesman said that following inconclusive post mortem examinations on the birds by the Animal Health and Veterinary Laboratories Agency, further tests were being carried out to determine whether they had been poisoned.

However, Natural England and the Wildlife Incident Investigation Scheme will not have the results until the new year.

Tests have not found any signs of pollution in the water and nor evidence of disease.