MPs are making a fresh push for a ban on parents smacking their children.
A cross-party group has tabled an amendment to legislation being debated in the Commons that would give youngsters the same protection against assault as adults.
But the Government is opposed to the change and rebel Labour MPs are angry that they have been refused a free vote on the issue unlike colleagues in other parties.
The move is being led by Kevin Barron, the Labour MP who chairs the Commons health select committee, who said the UK was out of step with other European countries.
He said: "We must act now to end the legal approval of hitting children. It is the responsibility of Parliament to ensure that the physical integrity and human dignity of every person is respected.
"The current law allowing so-called 'reasonable punishment' of children is unjust, unsafe and unclear, and must be abolished once and for all.
"I am disappointed that we have not got a free vote," Mr Barron added, arguing that it should be a matter of conscience and not subject to a Government whip. "Over 100 Labour MPs wanted a free vote but when it was brought up (at Monday's meeting of the Parliamentary Labour Party) it was made quite clear there would not be one."
The issue was last voted on by the Commons in 2004 when 47 Labour MPs rebelled and voted unsuccessfully for a ban. A compromise deal made it illegal for a parent to smack a child if it leaves a bruise but permitted a lighter smack or "reasonable chastisement".
Prime Minister Gordon Brown's spokesman said the Government was clear of the need to safeguard the interests of children but did not support an all-out ban on smacking.
That is in defiance of a call from the UK Children's Commissioners who earlier this year called for a total ban and attacked the Government for ignoring the views of children and professionals in refusing to outlaw such "violence".
