Areas of countryside remain off limits to ramblers despite the public being given legal right of access four years ago, say campaigners.
They believe Brighton and Hove City Council has failed to take on landowners who are blocking walkers from accessing parts of the downland. But the council said it had made progress towards opening up areas of outstanding natural beauty.
David Bangs, who has fought for walkers' right to roam, said several major sites on the Downs were still out of bounds.
He said: "The city council has given no clear political lead to its countryside service. What should have been a policy priority has been sidelined by the council's reluctance to take legal action against offending farmers."
Mr Bangs listed New Barn Farm, Portslade; Golf Farm, Hangleton; and Balsdean Bottom, north of Rottingdean, as three key areas the council had failed to open to the public.
A council spokeswoman said it was working with farmers at the first two sites but the third was outside of the authority's control.
She said: "Access is one of the four priorities of downland initiative, which has been widely consulted on and the council is making every effort to extend public access."
Mr Bangs said a host of downland areas were hidden. This included the Hog Plantation, East Moulsecoomb, which he said was only accessible through a hole in the fence on Ashurst Road.
A council spokeswoman said: "We have opened up access at Hog Plantation and are in the process of opening up further access at Ovingdean."
Is enough being done to open up areas of beauty? Comment below.
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