An angry surfer trying to reach a beach was confronted by a makeshift barrier of construction workers and security guards.
Ben Farwagi accused council chiefs and contractors of unfairly warding off surfers while carrying out work to strengthen sea defences off Brighton Marina.
Contractors threatened to call police when he tried to walk down a footpath traditionally used by surfers to get to the sea.
They then padlocked the main gate at the top of the footpath and warned Mr Farwagi not to crawl underneath or force his way through.
Action group Concerned Brighton Marina Surfers first threatened direct action protests when a £10.6 million, 18-month construction scheme started last January.
Some 60,000 tonnes of rock are being laid across 250m of beach between Brighton Marina and Ovingdean, including a series of four-tonne boulders and a 15cm layer of shingle.
The English Heritage-approved project will strengthen sea defences on Undercliff Walk following cliff falls around the marina two years ago.
Surfers were concerned the weight of the rocks and construction cranes would seriously damage a rare chalk reef and spoil their surfing, as well as denying them access to the water. However, talks between Brighton and Hove City Council and the British Surfing Association (BSA) produced a compromise allowing surfers access at the weekends.
Mr Farwagi was unhappy that surfers were now being turned away at all times, even on days when construction work was not taking place.
Instead they were being told to park their cars in Brighton Marina and scale a 20ft sea defence wall to get into the water.
Mr Farwagi, a director of surf services company 6ft Offshore, said: "It makes no sense to deny us access. They'd rather use up resources guarding the gate than simply have someone escort us down the 50ft walk."
One exasperated site worker said: "It's for their own safety that we're not letting people down. This is a construction site."
A council spokeswoman insisted the agreement was only meant to last until last Easter and said: "The Health and Safety Executive requires us to take all reasonable steps to ensure the site is safe for people."
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