Landowners claim first-time buyers could be driven out of the housing market by a national park in the South Downs.

The Country Land and Business Association (CLA) said the wealthy would be tempted to buy second homes in the new national park, forcing a rise in house prices.

Regional director John Biron said planning restrictions in the park could also prohibit building new low-cost homes.

He said: "The South Downs should not become the preserve of the rich. Expansion of the area creates further controls, which will inevitably lead to shortages of affordable housing around the Downs."

The association said the national park title should be excluded from the name of the park's ruling authority.

The comments were made a few days after the Countryside Agency agreed the draft boundaries of the park, to be consulted on later this year.

Some areas outside the existing Sussex Downs area of outstanding natural beauty are included inside the proposed boundary line, a move condemned by the CLA.

Chris Todd, of the pro-park South Downs Campaign, said the effect on house prices would be marginal.

He said: "Any increase the national park adds would be minimal, compared to house price increases in the South-East generally.

"They are clutching at straws.

"They know they are on the losing side and the Downs are going to get better protection regardless of what they do."