After the shock discovery of the swans along the River Seiont in Caernarfon late last week, fears grew bird flu had struck the region, but scientists have ruled it out as a cause.

Tests are continuing to discover what has led to the sudden loss of wildlife on a section of river between the Aber Swing Bridge and the Travis Perkins building on St Helens Road.

Caernarfon harbour master Richard Jones, who has been liasing with Defra representatives at the Welsh Assembly since collecting the dead swans, is hopeful the reason for the deaths will soon be discovered.

He said: "I am pleased it is not avian flu and we now hope to find out why so many swans have died. I have not known a situation like this before and it is can't be happening naturally."

A spokeswoman for the Welsh Assembly said: "Tests carried out on the swans from the River Seiont in Caernarfon have ruled out bird flu. Wild birds die for a variety of reasons and further examination is continuing to seek to determine the cause of death."

Seven birds were found to have died on Wednesday, June 11, with the harbour crews discovering another dead swan last Friday. They believe it may have died a couple of days earlier along with the other swans.

With no swans having been found to have died since, Mr Jones is now hopeful the mystery problem has passed and the swan population on the river will continue to thrive.

He said: "The number of swans we have here varies, but our checks in the harbour have found about 18 are still swimming around in areas close to where the others were found dead so hopefully things will now be okay.

"Local residents have been upset at what has happened. Swans are very elegant creatures and nobody likes to see them hurt in any way."