Three minke whales have washed up dead on UK shores in just a week due to unknown causes, prompting scientists to carry out a postmortem investigation on the third body.

A small common female minke whale (Balaenoptera acutorostrata) was discovered at Sea Palling, Norfolk, on Monday morning, just four days after another larger, 7.6 metre-long female minke was found nearby on Cromer East beach. A 9 metre-long minke was also found dead on a County Londonderry beach last Friday, the third time in the past three months that a whale has become stranded on a beach in Northern Ireland.

Including these three, there have been 14 minkes reported as stranded in the UK this year, the Natural History Museum said.

The 5-6 metre-long whale was found by the coastguard on a relatively remote area of Sea Palling beach, and is thought to have been dead when it was washed up. North Norfolk council, which has organised the removal of the body, said the whale had a hole in its jaw and abrasions on its flipper and body. It is not uncommon for the species to be found and stranded in UK waters.

Carl Chapman, Norfolk's cetaceans recorder and regional co-ordinator of Sea Watch Foundation, described the whale as "well-fed and otherwise healthy", and believes it may have become trapped in shallow waters while feeding close to the coast and may have died two or three days ago.

The minke whale washed up on Cromer beach, Norfolk. Photograph: PoppylandNature

A Cetacean Strandings Investigation Programme (CSIP) team from the Zoological Society of London is en route to Norfolk to carry out a three-hour postmortem and collect samples to carry out other tests.

Project manager Rob Deaville said the CSIP had turned down a postmortem on the first whale at Cromer because it was too decomposed, but that they would look at the Sea Palling case to see if there was anything of interest.

"If these two whales had washed up months apart, then we wouldn't have gone to either, but we think it's of interest that two have washed up in such short succession."

Deaville said access to whales was crucial for a postmortem as the high levels of fat causes them to decompose quickly.

"We're not sure what condition the whale is in, it's been taken off beach which can cause damage to the animal and it wasn't in the best condition to begin with. If this has been traumatic cause of death, for example it's been hit by boat or caught in a fishing net, we'll be able to tell quite quickly. But if it's death due to disease that might be hidden initially."

CSIP has been funded since 1990 by the UK government to collate data and carry out postmortems on cetacean strandings. Each year an average of 400-800 whales, basking sharks, seals, turtles, dolphins and porpoises are stranded along the UK's coastline – last year there were 600.

Whales may become stranded because they are sick or dying, which may disorient the animal and turn them inland, or because the fish they eat swim closer to the shore at certain times of the year and the whales get trapped in shallower waters.

Minke whales are found in the Atlantic, Pacific, Indian and Arctic Oceans, and in the UK commonly found in the mid- and northern North Sea. They are classified as low risk by the IUCN red list of endangered species, but threatened by human disturbance, habitat loss, prey depletion, pollution and entanglement in nets.

Minke whales were the only whales to still be commercially hunted until Iceland announced earlier this year that it had set a hunt quota for fin whales.