Federated Farmers is backing the Government's plan for rural broadband but says more money is needed.

Cabinet has signed off the roll-out and work is expected to start on the infrastructure early next year.

The Government is providing $48 million towards the $300m cost and will put a levy on the industry to deliver the rest.

Telecom says its earnings will be hit by costs of $56m a year, and its shares have plunged to a record low.

Federated Farmers chief executive Conor English said last night the Government's plan was "progress in the right direction" but it was just the first step.

"It's great that the Government has listened to Federated Farmers and delivered a plan that will see $300m invested over six years," he said.

"But in our view we are still quite short on the money side -- $300m is a start but we're not sure it will get fast broadband to every rural household and business."

Mr English said $500m would match expenditure levels for urban New Zealand.

"We simply think the Government needs to be much more ambitious for the one million Kiwis defined as 'rural'," her said.

"Federated Farmers is not talking baby steps but wants radical change. It's the ability to harness things like 3D and other leading edge technologies and this demands ultra fast speeds. We should aim high...rural New Zealand should be the envy of the world, not a follower."

Communications and Information Technology Minister Steven Joyce said Telecom had made representations claiming the levy was unfair, and it was entitled to do so.

"But generally, everybody else in the industry and the various user groups felt the approach we are taking was appropriate," he said.