Skeletons uncovered in Oxford city centre could have been the remains of Viking pillagers rather than settlers killed in a famous massacre.

Experts now believe the group of 37 men whose remains were found off St Giles’ four years ago could have been mercenaries raiding Oxford.

Previously they thought they were Danish settlers killed by English townsmen in the well-documented Brice’s Day Massacre.

The remains of men, aged between 16 and 25, were found at St John’s College in 2008 by Thames Valley Archaeological Services. It was thought at the time they were victims of King Ethelred the Unready, who ordered the killing of all Danish settlers in 1002.

Now, after chemical analysis and testing on the bones and teeth, staff from Oxford University’s School of Archaeology have put forward an alternative theory.

Professor Mark Pollard, director of research laboratory in the School of Archaeology, believes the skeletons might actually be those of Viking marauders who were caught and killed in retaliation, rather than Danish settlers living in the area.

He said: “When the bones were first found by Thames Valley Archaeology, they assumed they were from the massacre because they are from the right date and there was the historical link.

“There was evidence of burning on the bones, so it is a possibility. But the research we have done suggests that they were Viking raiders. It seems these were raiders who had come from all over the place. I think it was a collection of ‘freelance warriors’ – a bunch of bad lads basically, but it’s not conclusive.”

But Tom Hassell, former director of Oxford Archaeology, last night suggested another twist to the tale.

He said: “After the Brice’s Day Massacre, Oxford was attacked in revenge.

“The Danish army sacked Oxford in 1009 and the town succumbed to King Sweyn Forkbeard of Denmark fully in 1013. These men could have been part of those attacks, and maybe suggest Oxford put up a good fight.”

The original analysis, led by Cari Falys of Thames Valley Archaeological Services, showed the men were ‘attacked from both sides’ and appeared to be the victims of a slaughter rather than participants.This supports the claim that they were victims of Brice’s Day Massacre.

She said: “Usually when people have been involved in hand-to-hand combat you get evidence of this on the bones.

“You get cuts on the forearms as they defended themselves, but we have minimal evidence on the skeletons.”

Professor Pollard said his new information indicated diets rich in seafood and large robust frames, suggesting the men were not citizens, as those killed in the massacre would have been, but recent arrivals to England.