Thieves who allegedly broke into a nature reserve have put dozens of animals’ lives at risk after their habitats were left smothered in diesel allowed to leak from a stolen trailer.

Northward Hill in Cooling, near Rochester, was targeted on Monday night when a variety of items were reportedly stolen from an outbuilding, in addition to a 16-foot-trailer later spotted on CCTV being towed away by a small hatchback.

The trailer, which was seen heading along Lipwell Hill in the direction of High Halstow at around 10.20pm, leaked approximately 2,000 litres of fuel across the RSPB reserve in what has been described as “a mindless act of vandalism”.

Will Tofts, a warden at Northward Hill, said: “The fuel travelled through a soakaway and into a pond, covering the surface with the polluting fuel.

“This fuel is going to cause long term ecological damage to the pond and its fauna and flora. Since 2012, the RSPB has been working hard to improve the pond as a home for nature, such as planting reed plugs and shallowing the edges.

“This has seen some significant improvements, with reed warblers finally breeding in the reed this past spring and turtle doves, which have declined 93% in the last 25 years, using the shallow edges to drink from.

"Access to water close to nesting sites is vital to the highly endangered turtle dove and this small pond is vital in trying to maintain this species’ presence at Northward Hill.

“Marsh frogs are regularly heard croaking from the pond in the twilight hours, and there has also been a sighting of the elusive water rail skulking amongst the reeds.

"After the clear up operation is complete, it is going to take some years for these species to return and resume use of the pond.”

Breeding birds such as the lapwing, redshank, bearded tit, marsh harrier and avocet also call this part of their reserve their home, as do water voles.

Dubbed Buckland Fleet, it has been designated as a Special Protection Area by government legislation designed to protect the country’s most valuable habitats.

Northward Hill has been an RSPB reserve since 1956 and offers views across the Thames estuary from the London Shard to Southend. It is maintained by RSPB members and supporters, local community members and a team of volunteers.

Mr Tofts continued: “This mindless act of vandalism has resulted in these habitats and birds being put in danger of being affected by the pollution from the diesel.

“The RSPB along with the Environment Agency are currently working hard to ensure that this doesn’t happen so that the North Kent Marshes remain a fantastic wild and ecologically diverse place that we can all continue to enjoy.”

Police are investigating the alleged burglary and are appealing to anyone with information to come forward.

Anyone with information is urged to call the appeal line on 01634 792209 quoting reference XY/39208/16, or call Kent Crimestoppers anonymously on 0800 555111.