THE discovery of dead porpoises on the beach at Covehithe has fuelled speculation that sharks or a killer whale could be feeding off the east coast.

This week it emerged that the bodies of two porpoises with bite marks had been found washed up on the Norfolk coast at Horsey and neighbouring Winterton on consecutive days last month.

Yesterday, beachcombers came forward with photographs showing porpoises with similar injuries which were found at Covehithe and at Overstrand near Cromer.

All four of the bodies found were washed up within the space of about a month.

National shark expert Dr Ken Collins, who runs a shark-tagging programme at the University of Southampton, examined the image of the porpoise found at Covehithe by Mike Baker, from Lowestoft, and confirmed it appeared it had been bitten by a shark.

He said: 'There is no obvious damage of the kind that occurs if a porpoise has been caught up in fishing gear.

'It is not clear whether it was killed by a shark or a shark was scavenging on a dead porpoise.'

Dr Collins, who had previously confirmed likely shark bite marks on the Horsey porpoise, said it would not have to be a large shark, as a porpoise was only the size of an alsatian.

However, he said it was perfectly feasible for a great white shark to be found in our waters, although he admitted that the possibility would be a 'lightning strike'.

Mr Baker, 46, a painter and decorator of Essex Road, Lowestoft, said: 'I often walk along the beach at Covehithe and when I did so back in February I had my camera with me.

'When I saw the porpoise I thought,'wow', that has got bite marks and it looks pretty mutilated.

'I have seen a dead seal on the beach before but never a porpoise.'

The porpoise at Overstrand was found by Norwich shoe shop assistant Christina Evans, 58, who was with her partner Malcolm Reeve on the beach where they have a beach hut.

Ms Evans, who lives at Keswick Hall, near Norwich, said: 'We often watch seals from our beach hut, but the sight of a porpoise was unusual.'

She said they took a photograph of it at the time, in February, but only realised something sinister might be happening when they read details of the story.

Mr Reeve, 58, a technician, said: 'I don't want to think about whether there is a shark out there because I like going swimming.'

However, naturalist Percy Trett, from Great Yarmouth, who writes for the The Journal's sister paper the EDP, said he believed the attacks are more likely the work of a killer whale which could be found in the waters off Scotland and sometimes ventured into the southern North Sea.