Proposals that would ban the smacking of children are not about criminalising parents, Green MSP John Finnie has said.

Mr Finnie defended his plan for a Member's Bill to remove the defence of "justifiable assault", which allows parents to use physical punishment to admonish a child, as he launched a consultation on the move.

The Highlands and Islands MSP said Scotland was "out of step" with the rest of the world on the issue and had been "roundly condemned" by the UN.

The proposed smacking ban has the support of organisations including the Church of Scotland, the Association of Scottish Police Superintendents, NSPCC, Children 1st, the Children and Young People's Commissioner and Barnardo's.

Opponents argue the change in the law would erode the rights of parents.

Reverend David Robertson, a moderator at the Free Church of Scotland, argued the move was "completely unnecessary".

He told BBC Radio Scotland's Good Morning Scotland programme: "It's already against the law to hit a child on the head or to hit with an implement or to shake.

"This is going to criminalise good parents, just for tapping their child on the hand."

He added: The whole position is illogical, it's virtue signalling, it's middle class elites ... criminalising good working class parents."

Responding to the criticism on the same programme, Mr Finnie said: "This isn't about criminalising anyone. This is about supporting parents and most importantly giving the most vulnerable people in our society equal protection from assault.

"This is not about criminalising any more than legislation about seatbelts in cars."

He continued: "The express purpose of this Bill is to give equal protection for assault and that will prohibit physical punishment by parents and others caring for or in charge of children.

"That will be achieved by ending the current legal position that physical punishment of children can be viewed as justifiable assault."

Mr Finnie acknowledged there were people who had been smacked as children who believed it had done them no harm, but added: "We have to address the small minority who would be seriously damaged by this and all the evidence suggests that it is in every child's interest to find themselves in a safe and nurturing position, that's best for brain development. All the experts say this."

Members of the public will be able to respond to the consultation until August 4.

Scottish Liberal Democrat justice spokesman Liam McArthur MSP said: "It is shameful that our law continues to permit what it describes in Victorian fashion as the 'justifiable assault' of children.

"Despite widespread criticism from the UN, charities, police officers and social workers, Scotland remains one of the last countries in the EU that has not yet committed to abolishing this defence.

"Scottish Liberal Democrats have repeatedly pressed SNP ministers to act but without success. I hope they will now use this opportunity to finally update our laws and give children in Scotland equal protection from assault."

Children and Young People's Commissioner Tam Baillie said the consultation was "a positive step towards providing children with equal protection from assault".

He said: "It is hard to believe that our legal system continues to provide a defence of 'justifiable assault'. For me, there is no such thing because there is no way we can ever justify the hitting of a child.

"Research evidence is clear that physical punishment, no matter how 'light', has the potential to damage children. It also shows a clear link between the use of physical punishment and an escalation into more abusive behaviours."

The Rev Dr Richard Frazer, convener of the church and society council of the Church of Scotland, said: "The Church of Scotland supports the proposed Bill to offer equal protection to children.

"Whilst parents continue to have responsibility for the nurture of their children, as well as the creation of boundaries for them, we believe that the resort to violence should fade from being acceptable as we come to understand its negative impact."

Mary Glasgow, from the Children 1st charity, said: "Most parents in Scotland today have already chosen not to use physical punishment but we cannot continue to let our law give the mistaken impression that physical punishment can be helpful when we know, without a doubt, that it can harm."

A Scottish Government spokeswoman said: "The Scottish Government does not support physical punishment of children.

"We have no plans to introduce legislation in the area, but we will consider carefully the Member's Bill that we understand John Finnie intends to introduce.

"We continue to support positive parenting and we recognise that physical punishment can set children the wrong example and is not an effective way to teach children discipline."