A national park is the best way of preserving the South Downs, according to the Government's chief countryside watchdog.

Dr Victoria Edwards, a Countryside Agency board member, praised efforts being made to preserve the downs, singling out the Sussex Downs Conservation Board.

But she said a new national park authority would be able to do more by attracting more funding for farming and conservation projects.

Dr Edwards said: "It can act as no other body can, using its unique powers to work directly and independently to deliver what the downs need."

Many councils are campaigning to stop a new national park authority, which would take over planning powers on the downs.

The authority would have the power to draw up and enforce bylaws, limit car access and boost public transport.

Plans to give the South Downs national park status were announced by the Deputy Prime Minister, John Prescott, last year following years of campaigning by conservationists.

But the plans have been greeted with fanger by many councils in Sussex worried that a national park would boost visitor numbers leading to traffic gridlock and possible erosion.