Councils may be liable for huge damages after a landmark judgement by the European Court of Human Rights ruled that they were legally responsible for failing to intervene in cases of abuse.

The move comes after the court in Strasbourg awarded four siblings damages of £320,000 for abuse of their human rights plus £39,000 for costs and expenses.

In effect the ruling removed the immunity social services departments have from legal action if they fail to discharge their statutory duties.

The children had been abused by their parents over five years, and despite Bedfordshire Council being aware of this, it failed to intervene until the mother threatened to batter her children unless they were taken in to care.

The official solicitor, acting on the children's behalf, had taken the government to the ECHR because it was the only remedy open to them at the time they decided to take legal action.

The judges unanimously agreed that article 3 of the Human Rights Act, the prohibition of inhuman or degrading treatment, had been violated. They decided by 15 votes to two that the right to effect legal remedy, article 13, had also been violated.

Rob Hutchinson, Association of Directors of Social Services children and families committee chairperson, said: "Obviously we are concerned that this retrospective opportunity could open the flood gates for similar types of claims."

He added: "The implications could be, in the context of incidents that happened many years ago when legislation and practice was very different, increasing litigation, soaring legal costs and most worrying of all an overtly cautious approach to practice which could lead to more children coming into care."

Lyn Burns, Bedfordshire's director of social services, said: "We regret the suffering of the children prior to our intervention. Equally it was a long time ago and it is important to state that we have reviewed our procedures since then.

"It was possible to directly show our failure to act led to the circumstances that caused the emotional damage to these children."