Two Surrey grant-maintained comprehensives are planning to introduce partial selection from September amid hostility from opted-out colleagues.
Glyn ADT Technology College in Epsom, whose application for 30 per cent selection was turned down by ministers earlier this year, now wants to choose 15 per cent of its pupils.
Rosebery, also in Epsom, which has an application for 30 per cent selection with the Department for Education and Employment, has said it will go for 15 per cent whatever the decision.
Previous applications from the two single-sex schools have prompted record levels of opposition within the county with 300 statutory objections to their proposals for 30 per cent selection.
Both have been attempting to introduce some form of selection since 1993 - a year after they opted out of local authority control.
Their decisions now to go for 15 per cent are contained in letters to parents and colleagues which were sent out last month.
Schools usually have to publish statutory proposals for a change of character. However a Government circular issued in June said:" Selection of up to 15 per cent of the intake I is likely to be possible without the need to publish proposals." It goes on to state: "Each case must be considered against the circumstances of the school in question."
The proposals have upset two local GM heads as well as the local authority whose policy is to oppose selective education.
John Merrigan, head of Epsom and Ewell GM school, said: "Because it is legal doesn't make it right. For schools to want to select children on academic ability in 1996 with 2000 approaching is depressing beyond belief. Selection is divisive, unnecessary and destructive and it is all about improving results in the league tables."
And John Darker, head of the Beacon School in Banstead, said: "I am greatly saddened.
"These schools will try to select in order to avoid taking in the less able or pupils with special needs. You do much better in the league tables, tell everyone how marvellous you are but it is based on a false premise. It doesn't demonstrate valued added."
Mr Darker, chairman of finance and administration for the Grant-Maintained Schools Advisory Committee, said he would be objecting to the proposals.
Steve Clarke, Surrey County Council's deputy education director, said the proposals for 15 per cent selection from September were hasty and urged a year's delay.
"If you are a local person in Epsom and Ewell you will have been thinking about a school place for the past three or four years, and will have visited them. You will have assumed those schools are non-selective.
"To say now your child is going to have to do an exam, details unknown, in a place, unknown, time, unknown, is unreasonable. It is too late in the admissions cycle to introduce change now."
Governors at Rosebery said Government proposals to increase choice and diversity, together with the opening of a new school in Epsom, had convinced them it was correct to introduce an element of selection.
Stuart Turner, head of Glyn ADT, said: "The school has nothing to add to the arguments it propounded when seeking 30 per cent selection. Nothing has changed."