A policeman who bludgeoned his North-East wife and two of his four children to death with a hammer before hanging himself was arrested two years ago after a violent row with his wife, it was revealed last night.

PC Karl Bluestone, 36, was not charged after the incident, in which he allegedly held his children hostage.

Last night, campaigners against domestic violence condemned Kent Police for taking no action.

They believe this week's tragedy could have been avoided if PC Bluestone's colleagues had stepped in after the row in June 1999, when one of his children was injured by objects hurled across a room at the family home in Gravesend, Kent.

PC Bluestone was arrested for breach of the peace, but he was not disciplined or offered counselling after his wife refused to press charges.

An advisory file was sent to the Crown Prosecution Service because of the injury to one of the children.

One neighbour, who did not want to be named, said: "It happened during the day. I saw Jill run down the road to the end of my drive.

"She got into an estate car and drove off. I heard that the police were called and that he held his children hostage."

The Campaign Against Domestic Violence pressure group claimed Kent Police had "brushed under the carpet" the earlier incident.

Spokeswoman Teresa MacKay said: "Had he had some sort of counselling, this might not have happened.

"It would have been in the interests of him, and obviously the family, if Kent Police had looked into this."

Mrs MacKay said that police officers, alongside doctors, were statistically most at risk of perpetrating domestic violence because of their need to exert control in their working and home life.

She added: "It does not look good for the police if they're not putting their own house in order. It doesn't give confidence to other women and sends out the wrong message."

Mrs Bluestone, 31, who was born in Middlesbrough, was found dead in the kitchen at the rear of the house by police. The body of the couple's three-year-old son Henry was discovered at the bottom of the stairs.

Toddler Chandler was found in his cot with severe head injuries and died later in Dartford.

The couple's eldest son Jack, eight, was found outside the house with his sister Jessica, seven.

Jack is being treated for serious head injuries at King's College Hospital, London. He was in a stable condition yesterday.

Last night, Jessica was being comforted by Mrs Bluestone's parents, Alan and Judith Skerry, who live in Great Ayton, near Middlesbrough.

Police are not planning to interview the two children as they believe they have suffered enough.

They will try to piece together the events of the tragedy from forensic evidence and other inquiries.

Stunned local residents continued to leave floral tributes and personal messages outside the house in Marling Way yesterday.

A number of large teddy bears have also been placed at the scene. One carried the message: "Jessica, I hope you get better soon."

A former childminder of the four children said she had always believed that they were "the perfect family".

Julia Williams, 34, looked after the children until last November.

She said: "I was devastated when I heard what had happened. I just could not believe that such a thing could happen to young children.