Beekeepers are being warned to be on their guard after 30,000 honey bees were stolen.

The three hives were taken from a site near Great Glen and their owner fears the bees may have been killed by the cold.

Beekeepers are becoming increasingly concerned about the threat of hive-rustling.

The sharp decline in the number of colonies, due to disease and weather conditions, has led to an increase in the value of hives.

Last year, there was a spate of hive thefts nationwide, and beekeepers fear this may be spreading to Leicestershire.

Brian Cramp, from Groby, has 20 hives and is apiary manager for the Leicestershire and Rutland Beekeeping Association, which has about 200 members.

He said: "It is worrying. The problem is that many beekeepers cannot get insurance against theft now because so much of it is going on.

"In the past two years, people have realised the value of bees, so it is happening more often.

"We are encouraging people to brand their hives so if the police find them it may help them.

"There is not much more you can do. You just have to make sure they are well-secured and out of sight of the public."

The owner of the hives near Great Glen discovered the theft on New Year's Day.

The experienced beekeeper, who did not want to be named, fears the theft was so amateurish the bees could have been killed by the cold.

He said: "I estimate there were 10,000 bees in each of the hives. I fear they could all be dead now."

Bees cluster in a ball in the winter to preserve body heat.

He said: "I fear they would have been disturbed, breaking the ball cluster and making them vulnerable to the cold."

He said each of the hives was worth £200, if the bees were still alive.

John Randall, of Kirby Muxloe, the chairman of Leicestershire and Rutland Beekeeping Association, said: "This is only the third time this has happened to one of our members in the past 15 years.

"There are a lot of people who want to be beekeepers, but not enough bees.

"Unfortunately, there are some people who will steal them and then sell them on."

A spate of hive thefts in Whitby, Yorkshire, and Hampshire last year was blamed on the shortage.

In Leicestershire, colonies have declined by as much as 30%.

Experts say changes to agriculture, such as not leaving fields fallow, have reduced the amount of wildflowers available which are so important in providing food for the insects.

Diseases such as varroa mite have killed the bees, while climate change and pesticide use have also been suggested as possible factors in the insects' decline.

Christine Gray, spokeswoman for the British Beekeepers Association, said: "We are advising people to keep their hives away from public display and as secure as possible."

Police are investigating the theft in Great Glen. Anyone with information can contact officers on 0116 222 2222.