A British biotechnology company is claiming a breakthrough in the quest to create organs for transplant from pigs into humans.

PPL Therapeutics, based near Edinburgh in Scotland, says it has created the first so-called “double knock-out” pigs, genetically-engineered to lack both copies of a gene which causes rejection.

Scientists have given a mixed reaction to the claim.

Some experts say it represents a genuine advance, while others caution that it is one small step along a very long road.