A "devastating" arson attack has destroyed a £65,000 boardwalk and a section of grassland at a popular wetland.

The fire began at Hambrook Marshes, Canterbury, in the early hours of Friday morning.

Three fire engines and an all-terrain vehicle rushed to the scene just after 3.30am.

Fire crews discovered a board walk and a 100m-long stretch of grass were ablaze, and fought for several hours to bring the flames under control.

A fire service spokesman said: "Firefighters used a fogging unit, which produces a fine mist of water, to extinguish the blaze in the most environmentally friendly way.

"The footbridge which provided a walkway over boggy marshland was destroyed by the fire, and a cordon is now in place where it stood.

"The fire is being treated as suspicious."

Michael Water, a trustee of charity Love Hambrook Marshes which runs the site, said he thought it was a "prank call" when he was first told about the fire on Friday morning.

"It's in a completely wet area, and especially in the middle of winter, there's nothing that's going to go up in flames," he said.

But on arriving at the marshes, he found 80% of the boardwalk had been completely destroyed.

"I was just astounded," he said. "It's just gone. If a house burns down you've got a structure remaining, but the boardwalk is completely razed to the ground. It's just flat ground, with a crud of plastic ash on top.

"I think the plastic would be difficult to get started, but once it is going it'll really, really burn."

The board walk, made primarily of recycled plastic, cost £65,000 when it was installed in 2011.

It provides a popular route through the marshland, from which aquatic plants and wildlife can be spotted.

"You can't have the sensation of walking on water any longer," said Mr Water, of Rough Common. "But the wildlife is still there. I was just standing looking at the desolation yesterday and a kingfisher came and landed right there."

The trustees are stumped as to who could have started the blaze.

"We can't really understand what's happened," added Mr Water. "It seems vindictive, but as to 'why' I don't know.

"I can't imagine anyone deliberately going out at that time, in fairly miserable weather, with the intention of setting light to it - it just baffles me."

The Environment Agency has carried out a preliminary analysis, which reportedly found there has been no contamination of the water.

Love Hambrook Marshes aims to make the area safe, and will wait until Spring when the ground is firmer to remove "countless tonnes of material, some of the surface soil which is bound to be contaminated, plus the 20% of the board walk that did survive."

Mr Water says the trustees have not yet decided whether the boardwalk will be replaced.

"£65,000 10 years ago - it's going to be more than that now," he explained. "It's a huge sum, and would have the risk the same thing could happen again.

"For the moment, we're asking people who are very kindly offering support just to hold off until we've decided whether to replace it."

Fellow trustee Sian Pettman said the scene at Hambrook Marshes "looks like something out of the First World War battlefields".

She said: "Given the degree of destruction in such a damp environment, one can only assume that it was premeditated arson on a huge scale. It is devastating for such a tiny charity."

Police are investigating the incident.

Anyone with any information is asked to contact them on 01843 222289, quoting reference 46/28441/20.

You can also contact the independent charity Crimestoppers anonymously by calling 0800 555 111 or using the anonymous online form at crimestoppers-uk.org.

Read more: All the latest news from Canterbury