Holidaymakers who swim in the sea at British resorts are being warned to steer clear of a venomous fish, which appears to become more prevalent during heat-waves.

Weever Fish are found all round the British coast but only in sandy areas where the water is warm and shallow. The Weever and Jelly fish are the only two harmful creatures you have a chance of encountering on a British beach, says North Cornwall's Lifeguards and Coast & Countryside Service.

Holidaymakers should take the precaution of wearing flip-flops or other footwear so avoiding the excruciating pain suffered by Weever fish victims every year.

The Weever fish is most likely to be encountered at the low water mark where the fish buries itself in the sand leaving only its head and back exposed. You won't see a Weever fish but you will know it's there if you are unfortunate enough to stand on one since its back has a defensive sting mechanism. The sting can be very painful but will not cause permanent damage.

The sting feels at first like a sharp stab but this pain increases quickly for up to an hour and has been known to last for 24 hours and in some cases longer. It is therefore important to treat the sting quickly.

The poison it discharges is a type of protein and can only be treated by placing the effected limb in water as hot as the victim can stand without causing scalding.

A spokesman for the coastguard in Milford Haven said a 14-year-old boy was taken to hospital over the weekend after stepping on a Weever fish.

If you become stung, seek assistance from a lifeguard. Many, like North Cornwall lifeguards who are all qualified first aiders, have Aspivenin syringes which can painlessly draw out poison from the wound.

If you are away from a beach with lifeguard support, as soon as possible get the area which has been stung, invariably the foot, into hot water, this increases the blood flow which assists natural cleaning and healing, the heat also helps to breakdown the poison.