Independent retailers and residents in Newquay, Cornwall, have accused a local school of exploiting its new Academy status to sell land to Tesco for the development of a new supermarket.

The Tretherras Academy has announced plans to sell a portion of its land, including more than two acres of “open field that provides limited sports use”, in order to fund a rebuilding and refurbishment programme.

But campaigners claim the field is regularly used for sport and PE by the school, and leased out to external rugby and football clubs, yet say the school and Education Funding Agency refuse to call it a playing field.

They also accuse the school of secrecy. “We only found out because of a whistle-blower,” said Dr Val Martin, spokeswoman for campaign group Residents Against Inappropriate Development.

“No one has been consulted, including parents and pupils, yet the majority of people don’t want it. It’s the total opposite of localism because locals have no say with Academies.”

She said the proposals would also bring significant traffic and road safety issues, especially as pupils had to cross the road to get to the lower playing fields, “which are not fit for purpose anyway as they’re always flooded”. The school said it planned to upgrade the lower playing fields.

A town of 20,000 people, Newquay already has Morrisons, Asda, Sainsbury’s and Aldi supermarkets, as well as two Tesco Express stores.

Spar retailer Alex Moorse, whose store is located on the nearby Chester Road shopping parade, said the proposed supermarket would have a devastating impact on business. “It would have a worse effect than when the Tesco Express opened three years ago and hit our turnover by 20%.”

Dave Nichols of the neighbouring pharmacy added: “The school’s been completely underhand. It seems as if they’re trying to make as much profit as possible. Councillors say there are many reasons why it shouldn’t receive planning permission.”

Tretherras Academy press officer Marco Danielli insisted the school was committed to a public consultation once the plans had been finalised.