Electricity generation from the Hunterston B nuclear power station could fall by 40% this year after cracks were discovered in one of the reactors.

Colin Weir, station director at the North Ayrshire power plant, said the reduction in output came after the "right and appropriate" decision was taken to put one of the reactors offline after a "slight increase" in the number of defects.

A planned inspection of the graphite bricks that make up the core of Reactor 3 in March uncovered new "keyway root cracks".

These were found to be developing at a slightly higher rate than anticipated, operator EDF Energy revealed.

The reactor had been expected to restart a few weeks after it was taken offline, but that has now been delayed.

Bosses at the site, which opened in 1976, now expect the reactor to return to service before the end of the year.