Floating Chinese lanterns, the latest must-have lighting accessory for stylish summer parties, are being being denounced by farmers and animal welfare campaigners as “lethal litter” that can kill cattle.

The National Farmers’ Union has advised members to warn local hotels and country houses that organise outside functions that they could could face claims of negligence if any cattle are harmed by the wires that are left when the lanterns, like miniature hot-air balloons, have burned out. The lanterns can travel up to 30 miles once released.

Farmers’ leaders are to press for new guidelines covering the safety of the lanterns which have come to symbolise hope and good wishes in Chinese culture since they were first used in the 13th century.

Although no cattle deaths have yet been linked to the lanterns, veterinary experts are concerned that the wires which land on farmland can easily be picked up and chopped up with grass gathered to produce silage, the feed given to cattle during the winter. Other farm animals, horses and family pets are not at risk.

Gareth Hateley, a cattle specialist at the Veterinary Laboratories Agency, said: “The trouble with cattle is that they gulp food down at a great rate and take in a lot of food in one go. If there are small bits of wire in the feed it gets caught in the lining of their stomach and can pentrate the stomach wall and even break through the diaphragm into the heart. Wire is a real problem and it will kill a cow.”

John and Ruth Pidsley, who keep 100 pedigree dairy cattle on their 100-acre Thornton Hey Farm, at Ledsham, south Wirral, have had a number of lantern landings on their silage fields in recent weeks. They are extremely nervous it could be hidden in the animal feed, but will not know unless and until a cow becomes ill this winter.

Mrs Pidsley said: “This is happening all over the country but there has got to be some protection for cattle.” The couple have already raised the issue with their local hotel., which has recognised the concerns but declined to rule out future release of lanterns. Mr Pidsley said: “They told me their grounds were so extensive that a total ban on Chinese lanterns would be impossible to police and that if they wrote it into contracts they’d lose a lot of custom. But unfortunately my farm seems to be in a flight path. Who is going to take responsibility and compensate me if my animals die or need veterinary treatment?”

The Pidsleys’ concerns are just one of scores being dealt with by Robert Sheasby, rural surveyor at the NFU. He said: “Six weeks ago I don’t think I knew what one of these Chinese lanterns looked like. Now they seem to be everywhere. I am telling all members to contact country venues and to put them on notice it could be a negligible act to release lanterns near farmland. This might make them think twice about allowing lanterns. But we might need extra safeguards.”

The RSPCA is anxious to contact importers to see if the lantern design can be changed. Marc Cooper, its senior scientific officer, said: “There is a serious threat to cattle who ingest this wire. I think people should be more sensitive when they use these lanterns and importers should tell manufacturers overseas they need safer designs.”

One of the country’s leading suppliers, www.skylanterns.com, which sells almost 200,000 lanterns a year had been unaware of the risk the product can pose to cattle. The company’s manager, Grant Barry, said: “We issue instructions and urge people to be sensitive and to arrange pick-ups for the lanterns. But to be honest you cannot predict where they will land. They can go 20 to 30 miles in just 20 minutes. Rarely do people who release the lanterns see them coming down. But now I know about this problem I shall be certainly updating the instruction leaflet sent out with every box.”

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