Three wolves have been shot dead after the captive animals breached a perimeter fence and escaped from Colchester zoo in Essex.

The timber wolves were shot by zookeepers during an eight-hour hunt involving armed police officers and a helicopter.

Frenzied searches for the animals began at dawn on Tuesday when zookeepers found that five of the six wolves at the zoo had escaped through a damaged zoo fence.

One of the wolves returned of its own accord and another was captured after being shot with an anaesthetic dart.

The other three wolves had managed to leave the perimeter of the 60-acre zoo, prompting Essex police to dispatch a helicopter and armed officers to the scene.

Police warned the public to stay away from the area even as zoo officials said that the wolves were "naturally timid" and would not pose a risk unless cornered.

The hunt met a sad conclusion shortly after 4pm when the final missing timber wolf was discovered, believed to have been sheltering in thick undergrowth. The animal was shot dead.

A Colchester Zoo spokeswoman said the zookeepers were devastated by the death of the wolves and that a full report on the matter would be issued in due course.

The spokeswoman explained that the decision to shoot the animals was taken because an anaesthetic dart took 15 minutes before it had any effect and that it might not "work at all in a stressed animal".

The zoo added in a statement: "They are wild animals, and in an unpredictable situation they would have posed a risk to the public. We have obviously had a very difficult day and would be grateful for your consideration. We have nothing further to add at this time."

The cause of the damage to the perimeter fence of the wolf enclosure remains unclear and will be at the centre of the zoo's inquiry.