Dog owners are being warned about potential deposits of palm oil which have been washed up on north Norfolk beaches.
The substance, which is poisonous to dogs, has been spotted between Happisburgh and Walcott.
Palm oil deposits were found on several beaches last year, and left some dogs critically ill.
Dog owners should not allow pets to pick up and eat anything off the beach.
A spokesman for the Seal and Shore Watch UK said: 'Please be very careful if you are walking your dogs along our beautiful north Norfolk beaches.
'Big and confused seas have thrown up lumps of what is thought to be palm oil on our shores. Apparently, it is very palatable but extremely dangerous, if your dog eats it.
'Our medic Jon found massive lumps between Walcott and Happisburgh.
'He alerted Humber Coastguard, who in turn, tasked HM Coastguards Bacton. Our coastguards and Jon picked up several very large lumps and have reported there are many smaller pieces over quite a large area.
'There is no way of knowing when or where any more will turn up, but it will.
'Ships transport palm oil then have to pay to get their tanks cleaned. However, if they are at least 12 miles out and the sea is a certain depth they are legally allowed to flush out up to 100 litres into the sea per tank.
'It then congeals, picks up contaminants and fuel, then washes up on the beach if the weather conditions are right.
'The last time palm oil came to our shores, it was found as low down as Caister and a small amount was even found as far as up as Hunstanton, so we all need to be very vigilant.'
Refined palm oil is used in margarine, confectionery, chocolate, ice cream, soap, candles, and cosmetics, among other products.
People going to the beaches should take an extra carrier bag, pick up any palm oil they find, and dispose of it in the grey bins.
If you do see any deposits of palm oil on the beach, call the Seal and Shore Watch hot-line 07498 597448.
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