The campaigners claim that the 219ha development will destroy virgin beachs, olive groves and oak forests on the Black Sea coast.
One protester, Todor Karastoyanov, told the Guardian newspaper: ‘I ask myself whether Norman Foster really knows what he's getting himself in to… We want to try to stop him from making by building here, because it's immoral and he might not know that.’
In addition to a marina, artificial lakes and leisure facilities, the sustainable scheme, which has been in planning for nearly 20 years, will include five new ‘hill towns’ called Sky Village, Wilderness Village, Meadow Village, Cape Village and Sea Village, which will house 15,000 people.
Nadezhda Miksimova, of campaign group For the Nature, said a protest camp would be set up on the beach.
At the time of writing, Foster + Partners was unavailable for comment.