Anger erupted after Defra said it intended to reduce the level of elected representation on the body, which covers the west part of the county from the Tweed to the Tyne.

At present, 12 of the 22 seats on the authority are filled by local councillors.

Six are from Northumberland County Council, one from Berwick borough, two from Alnwick district and three from Tynedale district.

Four members represent the parishes which fall inside the National Park and the remaining six places are Secretary of State appointees.

But when the single unitary county council takes over next April, just six seats would be filled by elected councillors.

Of the remaining 16 seats, six would be filled by representatives for the parish councils.

The number of people appointed by the Secretary of State would rise from six to 10.

But county councillor for Rothbury, Steven Bridgett, who is an authority member, said: "What we are seeing is a last desperate attempt by central government not only to erode the democratic representation on the National Park Authority, but at the same time undermine the new unitary authority, which they imposed upon us.

"This move is nothing more than creeping quangoism, unelected and unaccountable to those people who live within the National Park, along with every other taxpayer."

North Northumberland MP, Sir Alan Beith, also slammed the proposals and said the Government seemed intent on dominating local decision-making.

"We are now being told that not only do we have a single unitary authority imposed on us but also that one effect of the reorganisation is that central government can boost its number of representatives on the National Park Authority at the expense of local representation," he said.

"Given that Northumberland County Council has to make sure that the different parts of the National Park still need to be represented, I am sure the council will need more than six places in order to do so, because it has to cover from the Scottish Borders down to Tynedale and the many different communities in the area.

"This move confirms many of our fears that local government reorganisation is being used to increase central government power and reduce the power of people living in the area affected."

In a written statement, the Minister for Biodiversity, Landscape and Rural Affairs, Barry Gardiner, said: "National Park Authorities have been independent bodies since 1997 and I believe that their independent status has helped them to deliver the National Park purposes and to meet both local and national needs.

"That independence might be threatened – or might seem to be threatened – if a single local authority appointed too high a proportion of their members.