Orchid thieves have stolen a significant percentage of one of Britain's rarest flowers.

The late spider orchid only grows at a few sites in Kent and on Friday one in Folkestone was targeted, with 30 plants plucked from the earth.

Neil Evans from Hardy Orchid Society said: "The theft represents a major loss to the population. They are only found in this country in a few sites in Kent. The local wardens do not want the site name published for obvious reasons."

Late spider orchids, which usually flower from next month, grow to between 10 and 50cm and carry up to 10 large pink and green petalled flowers with distinctive, spider-like dark brown velvety lips.

Early on Sunday thieves struck again in east Sussex, making off with 10 burnt-tip orchids from the sprawling Glynde Estate in the South Downs near Lewes.

The species' population has spiralled downwards over the past 50 years and it is also now considered rare.

The plant, which flowers between this month and next, is trickier to spot, with 10 to 15 white and purple flowers growing from spikes.

Mr Evans discovered the holes where the burnt-tips had once grown and reported the crime to Sussex Police.

Stealing protected flowers is a breach of both the 1981 Wildlife and Countryside Act and 1968 Theft Act and can result in a hefty fine and up to six months in prison.

It is not known if the two thefts are linked but orchid thefts are becoming increasingly common across the globe.

In 2019 some 3,000 plants of several orchid species were stolen from Germany's Taubergiessen Nature Reserve on the River Rhine.

Early and late spider as well as bumblebee orchids were among the haul.

Local biologist Dietmar Keil said at the time: "It will take at least 50 years for affected varieties to recover to some extent – if they can be saved at all."

It was the third theft in three years at the famous site.

Back then it was said single plants could attract bids of €100 online, while the rising number of thefts meant some sites in Europe needed round-the-clock surveillance.

In June 2016 one late spider orchid was dug up and taken away from the Folkestone Downs and another was dug up and thrown to one side, nearby, where it died.

The site, managed by Eurotunnel, was home to just six late spider orchids in 1990 but after grazing was reintroduced that number grew to more than 200 at the time of that theft.

At the time Kirk Alexander from the White Cliffs Country Partnership (WCCP) said: "This year would have been a bumper year for flowering by the late spider orchid and there was a good chance that the flowers would have set seed leading to new plants in future years.”

Following this weekend's thefts natural history writer and photographer Jon Dunn said: "Dug up wild orchids rarely survive - they rely upon very specific soil and mycorrhizal fungal associations to grow in the wild, and robbed of those conditions they're said to usually die. Whoever did this is pretty dim as well as selfish. What they've stolen is almost certainly doomed."

Kent and Sussex police have both been contacted for comment.