NATIONAL Trust volunteers have warned a 'tide of commercialisation' threatens to engulf Newtown National Nature Reserve.

They have said 'enough is enough' when it comes to visitors and fear for the future of the reserve if numbers continue to grow.

Two volunteers said they were sacked after objecting to the trust's plans for the visitor centre, and it is understood two more and a member of staff have subsequently quit. An application to improve the centre by replacing doors and windows and redesigning the building's interior — banishing a much loved mural to a small meeting room in the process — was approved by the Isle of Wight Council last month.

The row over the centre, coupled with plans to provide tea and cake, prompting concerns about litter, have seen volunteers decry moves to 'commercialise' the reserve, a haven for rare birds including curlews and lapwings.

Fifteen signed a letter to the trust's general manager on the Island, Tony Tutton, voicing their concerns.

Former volunteer James Allaway, who was sacked alongside Val Gwynn, a warden for more than 30 years, said: "These are small measures but it shows the direction the trust is moving in. It wants to encourage visitors, but if more people come they will harm this sensitive site. There is a fine line between between people enjoying the reserve and too many people damaging it.

"It's a nature reserve. It's not a visitor attraction in the same way as a stately home, but the trust doesn't understand that."

He said the number of visiting boats had increased from around 40 a day in the 1970s to around 200, and kayakers and paddleboarders risked disturbing nesting birds.

Mr Tutton said the trust could not stop more people visiting Newtown but did not actively promote it — but that same day an invitation to to a nature themed bear hunt was posted on its Facebook page.

"Our job is to look after the reserve and share it with visitors. That's why we are doing what we're doing, to make their experience more enjoyable. It will help them understand and appreciate the wildlife, which is what the volunteers want too," he said.