Plans for a new wave of grammar schools have been branded "morally wrong" by Labour former education secretary Lord Blunkett.
The peer, who when in office introduced a block on any further extension of academic selection, has urged a government rethink, with the focus "on raising standards for all and not the privileged few".
Lord Blunkett made his criticism during today's House of Lords debate on prime minister Theresa May's proposed reforms to allow new selective schools.
He said: "What we are presented with in this consultation paper is a diversion away from raising standards and once again on to structures."
Of the plan, Lord Blunkett added: "It's morally wrong, it's philosophically wrong, it's practically impossible to implement.
"I do pray that the government will think again and place emphasis on raising standards for all and not the privileged few."
'It's a failed policy'
Opening the debate, Labour peer Baroness Andrews had said: "This is a controversial policy. It's a failed policy. It's a policy which has been abandoned by all political parties as not fit for purpose over half a century ago.
"Grammar schools, whatever else they do, are not intended to work for everyone. By their commission and design they select and groom a small minority of academically inclined children, but other children pay a high price for this."
The idea that grammar schools promote social mobility is "risible", she added.
Liberal Democrat peer Baroness Humphreys said: "It is self-evident that selective schools give a minority of pupils a first-class education and the majority of pupils a second-class education."
Conservative peer Lord Cormack spoke of his own time as a grammar school pupil, and as a former teacher at a grammar school, saying that he found himself supporting the government's policy.
However, he felt that the age of 13 was a more appropriate entry point than 11.
Making her maiden speech, Conservative peer Baroness Vere – former executive director of the Girls' Schools Association – made the case for independent schools, arguing that most were not selective in admissions.
Pupils were streamed and set by ability and encouraged to reach their full potential, she said. "Independent schools are getting it right for children of all abilities and not just the most able," she added.