A national park in the South Downs would have at least five times as much money to spend as existing conservation bodies, according to the Countryside Agency.

Government funding for national parks means the South Downs should receive nearly £6 million a year, the agency says.

The Sussex Downs and East Hampshire areas of outstanding natural beauty, which would be combined in the new park, would in future share a budget of about £1 million.

Opponents of a national park, including most councils, have criticised the proposals for not including budget details.

Marian Spain, who heads the agency's designation team, said since the new funding formula was announced it had been possible to calculate what the South Downs might get.

She said: "This suggests a budget of at least £5.8 million. On top of this basic budget the park can also be given funds from government which recognise its particular circumstances, such as downland restoration, and can raise more money from grants from other sources.

"Other parks often receive up to a further one third of their budget in this way so this could mean another £2 million for the Downs."

The two existing bodies, the Sussex Downs Conservation Board and the East Hampshire Joint Advisory Committee, spend £1.7 million a year. That should drop to about £1 million because each would have to be reconstituted if the national park proposal fails.

National park campaigner and conservation board member Paul Millmore said the cash would come from the Government, removing the burden from local authorities.

He said: "It is clearly a win-win situation for the national park, the residents and visitors to the South Downs. We can't lose and it would be foolish to look a gift horse in the mouth so why are our councillors looking a gift horse in the mouth?"

The Countryside Agency is consulting on the proposals until February 28 and expects to hand a designation order to the Government later this year.

There is likely to be a public inquiry and it could be 2006 before the park is created.