Concerns have been raised over a rise in the number of children swallowing potentially harmful magnets.

A group of experts warned that magnets, commonly found in household toys, have the potential to cause “serious injury” when swallowed.

They warned that recently there has been a five-fold increase in the number of cases where children needed hospital admission after swallowing magnets.

In a letter published in the Archives of Disease in Childhood, paediatricians from some of the top hospitals in London said that children under the age of four commonly swallow “foreign bodies” without it causing any damage.

But they warned that certain objects can cause “significant harm” when swallowed.

There has recently been a focus on the harms which can be caused by button batteries when swallowed, but the authors of the letter said that other objects can cause harm as well.

“Magnets commonly found in household toys also have the potential to cause serious injury,” they wrote.

“We have all witnessed a recent rise in magnet ingestion within our respective centres.”

The letter states that from 2016 to 2020 a total of 251 children were admitted to paediatric units in London and Brighton with “foreign body ingestion”.

The authors said that there was a “steady increase in admissions” over the time frame studied.

Coins were the most commonly swallowed object followed by magnets and button batteries.

A total of 52 children were admitted after swallowing a magnet, they were aged between four months and 16 years.

And 42% of these children needed some sort of surgery.

The authors warned that when multiple magnets are swallowed this can cause the magnets to attract to each other and “trap” the intestine caught between.

This can lead to damage to the tissue or perforation, they said.

Out of all the children admitted after swallowing a foreign object, 10 suffered surgical complications. But most of these were among children who swallowed magnets, they added.

The authors said that magnetic toys are required to carry a warning but “most manufacturers do not display these”.

They wrote: “As a regional network of paediatric surgeons, we are extremely concerned with the recent rise in cases we have seen with foreign body ingestion and, in particular, magnets.

“This study has clearly demonstrated the growing problem with these objects and their associated morbidity.

“We recommend a strong public health campaign to increase awareness of the dangers of small, powerful magnets, especially those intended for toys, and to work with manufacturers in clearly warning purchasers of the dangers for children.