The blasts were considered by government scientists to be the prime cause of driving 70 pilot whales on to the beach at the Kyle of Durness in Sutherland in July 2011.
The shallow tidal inlet lies east of Cape Wrath, Europe’s largest live bombing range. Despite attempts to herd them back out to sea, 39 were left stranded by the tide. Concerted efforts by expert teams and local people managed to refloat a further 20, but 19 ended up dead.
A report by the Department for Environment, Food and Rural Affairs said three 1,000-pound bombs were detonated in the sea near the Royal Navy’s Northern Diving Group in the 24 hours before the whales were stranded. A fourth, 250-pound, bomb was exploded after the stranding began.
The bombs were left over from military exercises in which planes target Garvie Island, 4.5km from the Kyle of Durness.
Some bombs miss the island, fail to detonate and sink to the seabed, where they have to be located and disposed of. The report said the explosions could have damaged the hearing and navigational abilities of the whales, causing them to beach.
Highlands MSP Rob Gibson has written to Defence Secretary Michael Fallon demanding the MoD give assurances that this will not happen again.
A spokesman for the MoD said it accepted the report’s findings, adding: “The recommendations will be considered by the MoD and implemented where appropriate.”