Two young brothers were in the care of social services and may already have been reported to the police when they allegedly attacked and tortured two children with knives, bricks and burning cigarettes, leaving one for dead.

The boys, aged 11 and 10, had been placed with foster carers by Doncaster Council, whose child protection services were accused recently of a litany of failings. Serious case reviews have been ordered into the deaths of seven children in the area since 2004.

The brothers were held in custody for a third night as police continued to question them about the incident in Edlington, South Yorkshire, in which two boys aged 11 and 9 were subjected to a vicious assault.

The suspects had been living in the village for only three weeks.

Yesterday it was claimed that there had been a series of incidents in recent weeks in which local children had been terrorised by two young boys.

Complaints were made to social services and police about the behaviour of two boys, yet they continued to roam Edlington with apparent impunity, swearing at adults, allegedly throwing bricks at cars, and threatening and robbing children.

In the most serious incident before the weekend’s attack, police were told that an 11-year-old choirboy had been attacked by two young boys after being lured to an isolated spot.

Kerry Reynolds said that the pair punched, kicked and stamped on her son, Callam. “I was terrified,” Callam said. “They were shouting they were going to kill me.”

Ms Reynolds said that police officers visited her twice but showed no urgency over the case. She added that the two boys suspected of assaulting Callam failed to attend an interview at a police station on Saturday.

On the afternoon of that day, a nine-year-old boy was found, barefoot and soaked in blood, walking along a street in the town. His 11-year-old friend was later found, wearing only his boxer shorts and socks, unconscious at the edge of a pond a mile away. The man who found him thought that he was dead.

The 11-year-old boy’s scalp had been slashed. The blade of a Stanley knife was found nearby. He was airlifted to hospital and has now been taken off the critical list.

Jacqui Smith, the Home Secretary, described it as a “very serious and tragic case”. Gordon Brown was also reported to be shocked.

Ed Balls, the Children’s Secretary, said that the attacks were barbaric. “We were all deeply shocked by what we read.” he said. “It’s really very important that we don’t jump on a bandwagon and allow all groups of children to be demonised. The vast majority of young people should not be smeared by politicians trying to peddle rhetoric about a broken society.”

Doncaster social services confirmed last night that the brothers being held by police had recently been placed in foster care.

Paul Hart, the council’s managing director, said: “This is a truly shocking and upsetting incident and we are working closely with our partners to assist the investigation.”

A spokesman for South Yorkshire Police refused to discuss any of the incidents preceding Saturday’s attack “due to the constraints of the law relating to such matters”.

Mr Balls sent a new management team to take over Doncaster Council’s children’s services last month after it emerged that reports had warned of social workers being overwhelmed by their caseloads. One worker said that details of vulnerable children were “buried quite literally in a pile of other referrals”.

The independent Mayor of Doncaster, Martin Winter, announced that he would not stand for reelection in June.

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