Poison and hate mail amid the coconut palms of Queensland

They are a symbol of Australia's tropical north, their rustling fronds framing picture postcard views of white sandy beaches and the azure waters of the Coral Sea.

But the northeastern state of Queensland's coconut palms are under a two-pronged attack from councils who fear they will drop their bulky fruit on the heads of unsuspecting passers-by and conservationists who say the trees are crowding out native rainforest.

So passionate is the clash that one environmental group has taken the law into its own hands, poisoning the trees in a covert campaign of sabotage.

'The whole bloody coastline is infested,' said environmental biologist Hugh Spencer, who has received hate mail for leading the charge against coconut palms. He also heads the Australian Tropical Research Foundation. 'It's a cancer. If they're left to their own devices, you end up with a monoculture. But if you tell people they're a weed, they go berserk.'

Marching down the beach at Cape Tribulation, in northern Queensland, Dr Spencer passes the bikini-clad backpackers sunning themselves on towels. He heads for a thick grove of Cocos nucifera (coconut palm), crashes into the tinder dry leaf litter and points out a tiny hole in the base of a particularly tall specimen.

'We put poison in there. It's entirely illegal, I might add. We do it on days when the weather is bad and there's no one on the beach,' said Dr Spencer.