The government had argued that some parents with mental incapacity who were deemed to require legal representation could end up suing the government under human rights rules if they were not provided with state-funded lawyers.

However, Labour and the Liberal Democrats voted to annul a measure extending such provision on the grounds that most children’s panel chairs did not want more lawyers involved in proceedings because this could make them more adversarial.

As the vote was passed, furious SNP members recorded their dissent and accused the Labour convener of the committee of failing to be impartial, while in response Labour MSP Karen Whitefield claimed children’s minister Adam Ingram had misled the committee by saying he had repeatedly offered to brief members on the issue.

The issue will now come before the whole parliament amid warnings that if the annulment is upheld the government will be open to the kind of human rights challenge that saw millions of pounds paid out to prisoners over the slopping-out controversy.

Mr Ingram yesterday said that the extension to state-funded representation would only cover about 250 cases a year, half of one per cent of cases. He added that anulment would “mark a new low for any committee of this parliament.”