The shy mammal was found drowned in the trap set to catch crayfish on the River Ouzel at the weekend.

The exact location is being kept secret by Milton Keynes Parks Trust but it is understood to be less than a mile from the heart of the city.

That the animals have been seen in the area is being hailed as a success for conservationists, but the death is just one of a growing number caused nationally by the illegal traps.

Colin Savage, the Parks Trust's landscape officer, described the setting of the trap as irresponsible and the otter's death as
"incredibly sad".

The male otter's body is being examined by experts from the Environment Agency.

It is hoped the animal's partner, which has also been seen, will find another mate.

Yesterday Trevor Johnson, chairman of Milton Keynes Angling Association, also slammed the illegal traps which can kill other river mammals.

"American Signal Crayfish which are decimating our native crayfish and damaging river banks can be trapped legally with an Environment Agency permit.

"Some people also legally catch them for their meat.

"We have a licence to trap them but we use the approved traps which are otter proof and numbered," he said.

Otters can swim inside the illegal traps to eat the bait inside and are unable to get out.

The Environment Agency said otters are a protected species. Killing them is illegal and prosecution could lead to a £5,000 fine or up to six months prison.

The Parks Trust has urged anyone who sees fish traps being set or finds a dead otter to call the EA's hotline on 0800 80 70 60.