A key part of flagship legislation on child protection is being ditched to salvage the main part of the law and get it passed before the May election.

While ministers press on with safety checks on hundreds of thousands of adults who work with children and vulnerable adults, they want to counter the perception that risk assessments are nonsensical and getting out of control. They admit there is a need to reassure the public that they can still help with a school dance, sponsored walk or walking children to school.

Executive ministers have bowed to pressure from critics of the Vulnerable Groups (Scotland) Bill, and have accepted significant changes are needed.

Robert Brown, Deputy Minister for Children and Education, will tell MSPs when they vote on the bill this week that the third section is being dropped. That would have placed a legal requirement on public agencies to share information on those who work with children and vulnerable adults to flag up warnings when they are at risk from people who pose a danger.

However, he says he is not able to meet back-bench demands to provide detailed plans for the workings of the vetting regime before the bill completes its passage through Holyrood in March.

The bill was introduced in response to the Soham murders of 2002. The Bichard Report found police and other agencies had failed to share information about school janitor Ian Huntley, who killed two schoolgirls. Legislation has been needed to plug the gaps for both Scotland and the rest of Britain.

Mr Brown hopes information will still be shared in Scotland without a legal requirement, and that MSPs after the election will add the measure to planned legislation reforming the children's hearings system. He intends to introduce a code of conduct for sharing information, even without the law requiring one.

Part three of the bill had not been put out to public consultation, and involved complex issues including patient and client confidentiality for doctors, sexual health workers and women's refuges. "It was threatening to foul up the whole thing," Mr Brown said. "The timing is tricky. There's no scope for slippage."

He is not giving ground on the issue of vetting of up to one-quarter of Scots adults, claiming the figures have been exaggerated.

It has been described by critics, including Children's Commissioner Kathleen Marshall, as overkill, creating an expensive bureaucratic burden on voluntary groups and discouraging adults from offering to work with children.

Mr Brown says there is a need to address the perception that vetting and safety requirements for working with children are disproportionate to the risk.

He said he wants to counter this with clear guidance about what the law requires. "There's no doubt the issue of people being put off more hazardous outdoor activities and the lack of volunteers coming forward are things we've got to get right," the minister said. "We need to take action to try to restore a bit of balance."