The Vatican has responded to a report detailing sexual abuse by hundreds of priests in the US state of Pennsylvania, saying the abuses described are "morally reprehensible".

It comes after a grand jury investigation in Pennsylvania alleged that 301 Catholic priests in the state sexually abused children while serving in active ministry.

Investigators received 'detailed accounts' of more than 1,000 victims - with the grand jury saying it believes the actual number of victims was in the thousands.

The abuse is alleged to have occurred over 70 years in six dioceses.

The grand jury also found there was a "systematic cover up spanning decades by senior church leaders in Pennsylvania and the Vatican".

In a statement responding to the report, Vatican spokesperson Greg Burke said Pope Francis understands how the abuse described in the report can "shake the faith and the spirit of believers".

The statement notes: "There are two words that can express the feelings faced with these horrible crimes: shame and sorrow.

"The abuses described in the report are criminal and morally reprehensible. Those acts were betrayals of trust that robbed survivors of their dignity and their faith."

It adds: "Victims should know that the Pope is on their side. Those who have suffered are his priority, and the Church wants to listen to them to root out this tragic horror that destroys the lives of the innocent."