AN investigation has started into how sewage poured unchecked into a river for nearly five hours last week.

Waste overflowed into the Swan River in Warminster after a blockage in the sewers underneath nearby playing fields.

Water bosses sent a team with high-powered hoses to clear the jam, after sewage escaped between 7.30am and 12.20pm on January 5.

Now environmental experts are assessing the damage caused by the spill, which residents claim is an ongoing problem.

A spokesman for the Environment Agency said: "Initial tests revealed no fish have died but samples were taken and we discovered high levels of ammonia.

"We will be discussing ways to prevent this from happening again."

The Environment Agency has not ruled out the option of prosecuting Wessex Water, which is responsible for the maintenance of the sewers, and is carrying out its own investigation.

Town councillor Les Rose spent over three hours with environmental experts during the clean-up operation.

He said: "Things like this just should not happen, we live in the year 2004, there must be measures to stop this but it is an on-going problem."

Swan River, or The Were, flows through the Lakeside pleasure grounds and playing fields and feeds into the River Wylye.