Britain’s only killer whale pod will be wiped out by the end of the century because of deadly chemical pollution in the seas around the UK, a report has warned.

New analysis by an international team of researchers including the University of St Andrews and the Zoological Society of London has found that half of the world’s population of orca will vanish in the most heavily contaminated areas.

The chemical pollutants, polychlorinated biphenyls, or PCBs, were once widespread in paints, adhesives and electronics but were banned in the 1970s.

However the paint from old bridges, boats and buildings can still flake into the sea, or leach into waterways from disused mines where it was used as hydraulic oil or from landfill sites.

Around the British Isles, killer whale numbers have halved to around 10 because of the the chemicals and the mammals are likely to vanish altogether in the coming decades, the new research found.

Last May, a dead orca called Lulu was found washed up on the Hebridean Isle of Tiree with the highest levels of PCBs ever recorded and it is feared the rest of her pod will have the same level of contamination, which can impair the immune system and damage fertility.