Prisons are witnessing a massive surge in elderly inmates - many of whom have been found guilty of sex offences - and are completely ill-equipped to cope, a leading criminologist warned.

Nearly 4,000 over-60s are now behind bars, with numbers having soared by 130 per cent between 2002 and 2013.

Professor David Wilson, Birmingham City University, said there is no nationwide strategy for coping with the increased presence of older inmates in UK prisons.

"Four out of 10 of these prisoners were convicted of sex offences and people over 60 are the fastest growing age group in the prison estate, yet there is no national strategy for the elderly who get sent to prison.

"While there are some pockets of good practice at prisons the Prison Service needs to develop a strategy to cope with this fastest growing section of the prison population or they will simply be failing in their duty of care to the elderly people that they are locking up."