Social workers should be under a legal duty to see any children who might be at risk on their own during the course of a protection inquiry, the National Society for the Prevention of Cruelty to Children said today.

The NSPCC is calling for a change in the law in England to prevent a repeat of cases like that of Birmingham seven-year-old Khyra Ishaq, who died of starvation and neglect in 2008 after social workers failed to see her.

The charity's head of policy Diana Sutton said a change in the law would give social workers more power to get past manipulative parents who intimidate or conceal their children to try to hide the evidence of their mistreatment.

Ms Sutton told BBC Radio 4's Today programme: "Too often we see cunning and manipulative parents actually trying to hide abuse from social workers.

"In case after case, we see that children haven't been spoken to on their own, so they haven't had an opportunity to actually say what is really going on.

"We don't want this to be a heavy-handed tool. We want it to be a legal change that will drive a change in practice so that it becomes routine that they have to - as part of the child protection inquiry - talk to the child on their own and establish directly with the child what is going on."

If they are not able to conduct a private interview with the child, social workers should be required by law to record the reasons why," said Ms Sutton.

The chief executive of the British Association of Social Workers, Hilton Dawson, said that social workers already had the power under the Children Act to seek a court order requiring parents to allow them to see children on their own.

Mr Dawson told Today: "If parents blatantly refuse and manipulate or threaten to set the dog on social workers, then they have exactly the same recourse as what the NSPCC are proposing."

And he added: "We welcome the NSPCC raising this, but we think that there are bigger issues around the number of social workers, the workload of social workers, training and support of social workers and the career structure that we need to keep the most experienced social workers in frontline practice."

But Ms Sutton said that a court order was a "heavy-handed tool" which tended to be used later in the process of a child protection inquiry, while the NSPCC's proposal could make a private conversation with the child a routine and early part of every probe.

She said: "At the moment, there is a duty to listen to the child's wishes and feelings, but that is obviously not the same as seeing the child on their own."