The boundary of the proposed South Downs national park should hug the northern edge of Brighton and Hove, wildlife groups told a public inquiry.

City conservationists want many greenfield sites between the A27 and the built-up area to have the same protection as other parts of the South Downs.

Dave Bangs, representing the Brighton and Hove Community Wildlife Groups Forum, said the sites were too vulnerable to be left outside the park.

He said: "We can afford nothing less than a cling-film boundary around the northern edge of the urban area."

Mr Bangs said fields north of Mile Oak, Portslade, should be included because they were a threatened gateway to the Downs beyond the A27 and were widely used by many local people.

Campaigners have also called for a small pocket of land around Foredown Tower, Hove, to be included for similar reasons.

The Countryside Agency said vulnerability was not a reason for including land in the park and only nationally-important landscape should be designated.

Sites around Brighton and Hove such as Benfield Valley, Toad's Hole Valley and Whitehawk Hill will be considered at the hearing over the next few weeks.

Sites which have area of outstanding natural beauty status are likely to lose the protection if they are not included in the park.

The inquiry, taking place in Worthing, is due to continue until September.