The protest, which is being organised by the Children are Unbeatable! Alliance, has been timed to coincide with the report stage of the bill in the House of Commons.
An amendment to abolish the legal defence of reasonable chastisement, which dates from the 19th century, is being tabled by Labour MP for Wakefield David Hinchcliffe, chair of the Commons health select committee. He said, 'There is nothing reasonable about this archaic and unjust law.'
Tony Samphier, the alliance campaign adviser, said, 'It is vital that professionals working with families, and everyone concerned with children's well-being, turns out to support the lobby. MPs must be left in no doubt that the professional consensus is that equal protection is the only credible, safe and just way forward. Hitting children is as unacceptable as hitting anyone else, and the law should say so in the 21st century.'
NSPCC director Mary Marsh said, 'Children are the weakest and most fragile in our society. The least we should do is afford them equal protection, backed up by mass public education on positive parenting and greater support for parents.'
The alliance, which comprises more than 350 organisations, including the NSPCC, Barnado's, the National Children's Bureau and the National Childminding Association, said that nearly 200 MPs and members of the House of Lords have signed up to its aims.
The campaign received a boost recently when the parliamentary joint committee on human rights, in its report on the Children Bill, called for equal protection to meet human rights obligations under UN and European treaties.