Council leader Ruth Dombey has said she is "confident" a new secondary free school in Belmont can cope with rising demand for places in the short term, despite the Government's belief the site is too small.

The comments came after MP Tom Brake demanded his Liberal Democrat colleagues explain their decision not to back the Education Funding Authority's (EFA) plan for a new school at Rosehill Park.

In a statement released by Sutton Council's press office, Coun Dombey said: "The council is confident that the development of a new secondary school on the Sutton Hospital site will provide the school places needed initially.

"If an additional secondary school is required in the longer term then the council will have to consider all available sites."

It is predicted Sutton will need a new school by 2017 to cope with demand for secondary places. But the council has admitted in a letter to the EFA that blocking the Rosehill project may delay construction.

In July the EFA chose Rosehill's all-weather pitches as its preferred site for the borough's newest secondary, flying in the face of Lib Dem hopes to develop a school and cancer research hub at the former Sutton Hospital site in Belmont, where the council bought land for £8m in March.

The EFA made its decision after a feasibility report, commissioned by the council, found the Belmont site was "very restricted".

Coun Dombey also defended the decision to support construction of a new primary school on a Metropolitan Open Land (MOL) site in Hackbridge, having cited Rosehill's MOL status as one of the reasons her group did not want a school there.

Her statement added: "When the council was looking for a site for the new Hackbridge Primary School, there was no alternative brownfield site option in the area.

"Therefore we proposed the use of MOL for the primary school's annex building. We did this with great care knowing that there were other factors supporting the development.

"These factors included support from the Greater London Authority, and the Department for Education (DfE), that the application was for a zero-energy exemplar school building, and that, unlike Rosehill, the land did not have formal access for the public.

"We are now in a position where we do have a brownfield site available for the new secondary school. Therefore the council has to give preference for it over MOL or green-belt land."

A DfE spokesman said: "The hospital site would be extremely small for a secondary school meaning any building would have to be multi-storey with limited outside space."

Conservative group leader Coun Tim Crowley said: "Sutton’s Lib Dems have decided to play a reckless game of chicken with the DfE.

"By refusing the Rosehill site they are gambling that the department will blink first and build in Belmont.

"They seem desperate not to admit they’ve wasted £8m buying an unsuitable plot of land that they now can’t do anything else with.

"The Rosehill site must proceed as a matter of urgency, or hundreds of pupils risk being left without a school place in 2017."