Image caption The injuries have occurred on both common and grey seals

The mysterious deaths of more than 30 seals washed up along the east coast of Scotland and England in the past two years are being investigated.

Each of the carcasses had a single, smooth-edged cut which started at the head and spiralled around the body.

Experts said it was not known what had caused the "corkscrew" injuries, which were not consistent with fishing nets or boat propellers.

Members of the public who spot a seal carcass have been urged to report it.

Seven seals have been found with the corkscrew wounds - which affect both common and grey seals - in St Andrew Bay and the Firth of Forth in the past two months.

It is critical that we establish the cause of these strange seal deaths and do all we can to protect our seal populations Richard Lochhead, Scottish environment secretary

Six similar incidents in the same areas in 2008 and 2009 have since been uncovered.

In addition, four incidents were reported in Norfolk in July, part of 20 such occurrences in that area over the past year.

Similar unsolved seal mortalities have also been reported off the Atlantic coast of Canada over the past decade.

Scotland's Environment Secretary Richard Lochhead has asked scientists at the Sea Mammal Research Unit (SMRU) at the University of St Andrews to investigate the potential cause of the seals' deaths.

He said: "Seals form an important part of Scotland's rich marine environment and it is critical that we establish the cause of these strange seal deaths and do all we can to protect our seal populations, particularly as numbers have reduced in recent years.

"I would encourage any member of the public who encounters a seal carcass to contact the Sea Mammal Research Unit, which will help to establish the scale of these issues.

"The Scottish government has already taken decisive action to provide additional protection for the endangered common seals, as set out in our new Marine Act."

Significant declines

Professor Ian Boyd, director of the SMRU, said it was important to establish how the seals died, and how widespread the problem might be.

He added: "This will inform any consideration of population impacts and potential mitigation.

"This investigation is important because these deaths come on top of significant declines observed in some Scottish common or harbour seal populations.

"SMRU welcomes any reports from the public of dead seals being washed ashore."