Two new aircraft carriers may be rendered useless because the military base where they will dock next year is badly out of date, a new report has found.

The Ministry of Defence is facing an £8.5billion black hole in funding over the next 30 years because it has failed to invest enough money in the estate and vast repair works are now required urgently.

Some bases and training sites are falling into such disrepair that they may be shut down altogether, affecting military capability.

Power cables at the Portsmouth base which will supply the two new £6.2billion carriers are over 80 years old and need replacing but there is no money to upgrade them, the National Audit Office warned.