Children make more than half a million prison visits a year, Barnardo's has revealed.

The charity warns that these visits are taking place in a "policy black hole" and raises fears they may be failing to meet the needs of hundreds of thousands of vulnerable children.

Barnardo's is releasing the figures obtained under the Freedom of Information (FoI) Act for about 120 public prisons in England and Wales that show last year children made an average of just under 10,000 prison visits a week - the size of 39 primary schools.

On average, around 18,000 children visited a prison every month, a total of 506,694 visits last year, according to the Just Visiting briefing.

Barnardo's chief executive Javed Khan said: "Children are the forgotten victims of the prison system. Every week thousands of innocent children pay the price for crimes they did not commit.

"These children may spend tiring hours travelling to a prison and then several more hours stuck inside waiting to see their dad or other relative.

"They may be met by frightening guards and sniffer dogs, and subjected to a 'rub down' or more detailed body search.

"Children of prisoners have done nothing wrong and do not deserve punishment for their parent's crimes.

"The distress of a prison visit can be long-lasting, a child should not be left to pick up the pieces on their own.

"Prisoners' children are completely overlooked. We want to see these children brought out of the shadows and given the support they need."

The full scale of visits taking place in England and Wales will be even greater as the FoI requests do not cover fourteen private prisons.

Barnardo's called on the Government to introduce a "national action plan" to plug the "policy black hole" around prisoners' children.