Parliamentary under secretary for schools Stephen Twigg told the education and skills select committee on Monday that the provisions, which will be included in the forthcoming Children's Bill, will require councils to police admissions for looked-after children.
Under revisions to the admissions code of practice, councils and schools with their own entry policies are recommended, but not mandated, to give top priority to children in care in over-subscription criteria.
This year, councils made 25 objections to the Office of the Schools Adjudicator against schools that had failed to prioritise children in care, all of which were upheld.
However, schools minister David Miliband, giving evidence alongside Mr Twigg, ruled out forcing change from the centre, for instance by making the admissions code mandatory.
He said: 'The thinking of going down the code route was made in response to the overall needs of the admissions system, to make it less bureaucratic and more attuned to local needs.'
He said the government's job is to ensure admissions procedures are transparent and fair, rather than to determine their content.
He added: 'Different parts of the country make different choices.'
However, despite the introduction of admissions forums to co-ordinate policies within localities, evidence from the Audit Commission and Ofsted has shown that partnerships are often poor between councils and autonomous schools (LGC, 21 November).
Committee chair Barry Sheerman described the system as 'laissez-faire'.