Campaigners have vowed to continue fighting thousands of new homes in the countryside despite a major setback.

Haywards Heath and Burgess Hill town councils appealed to extend the consultation period on where to build 15,000 homes in the district.

The public was given eight weeks, which ended today, to view and comment on the core strategy, a document that will determine development in the district until 2026 when it is approved.

The planning bosses' request for an extension was turned down by Judith Hewitt, planning officer at Mid Sussex District Council.

The authorities wanted extra time to employ consultant planners to help draft their responses.

Haywards Heath mayor Richard Goddard said: "We commissioned an independent report to test the assumptions made in the core strategy.

"The consultation period was unrealistic for us to go through that and all the processes associated with it.

"We hoped members would have more time to consider our report to add to our response. But we will just have to submit what we have."

The length of time of the consultation has been criticised by senior councillors.

Cabinet member for planning at the district council Susanna Kemp said: "We've all said it's an extraordinarily short period of time to examine an important document like this. If you are sick or on holiday, to get things organised in that space of time is quite difficult."

Elements of the planning document have come under criticism from community groups across the district. A total of 12 sites have been proposed, some of which will involve developing huge areas of the Sussex countryside.

A proposal for 1,500 homes to the west of Burgess Hill led to Hurstpierpoint schoolboy Callum McHale to lead a 700-strong protest march last weekend.

Campaigners say the development is unsustainable and will result in the town encroaching on neighbouring villages.

A residents' association on the outskirts of Haywards Heath employed a consultant planner to help draft its objections to 300 homes at Hurst Farm and a further 700 at Sandrocks.

The Fox Hill Association believes the proposed housing is unsustainable because there is no infrastructure to support it. It hopes its arguments will block any proposals to build on the strategic gap between Haywards Heath and Burgess Hill.

The district council, which will approve the final draft, said there had been a strong response to the consultation.

It will publish a summary of the responses in June and a more detailed report in the autumn.

Can the area cope with so many extra homes? Tell us what you think below.