More than a fifth of existing grammar schools are preparing bids to expand in the wake of £50m funding.
At least 35 selective schools - of which there are 163 in England - are considering a share of the expansion funding announced by the government to help create thousands of new places.
Analysis from campaign group Comprehensive Future calculates that an additional thousand pupils could attend grammar schools a year - if all proposals for expansion are approved.
Campaigners have criticised that spending is going on academic selection during a school funding crisis - and they argue that expanding grammar places causes “serious problems” for nearby secondary schools.
Grammar schools have under a month to submit bids for the £50m fund - which schools minister Nick Gibb has said could fund up to 4,000 places a year. Schools will be able to access cash from September.
As part of the bids to government, existing grammar schools have to set out what action they will take to boost the number of disadvantaged pupils they admit following criticism of a lack of diversity.
Comprehensive Future found consultations for expansions on the websites of 35 selective schools across England - from Kent, London and Essex, to Devon, Manchester, and the West Midlands.
It is possible that other grammar schools are seeking funding but have not put their consultations - which are supposed to run for four weeks - online ahead of the August deadline.
Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said they had “deep concerns” about the further expansion of grammar schools.
