Some drivers will face a rougher ride if the Federal Government cuts funding designed to give local roads a fair go.

The “supplementary local road funding” - now worth about $18m a year - was established by the Howard Government in 2004.

At the time, the federal government accepted that the legislated formula treated South Australia unfairly.

SA has 11% of Australia's local roads but the formula gives SA only 5.5% of the funding.

Howard's government introduced the “supplementary” funding to give SA a fairer share.

But the Assistant Minister for Infrastructure and Regional Development Jamie Briggs, said on ABC radio this week that “there's no money in the budget” for the supplementary funding.

This is despite a Commonwealth Grants Commission recommendation that SA should get 8.7-8.9% of allocated road funds.

SA Local Government Association President Mayor David O'Loughlin said the supplementary road fund had been extended on a three-yearly basis ever since its introduction, but both Coalition and Labor governments have failed to fix the underlying formula.

“If this funding is not extended in the May Federal Budget, SA Council road programs will be trashed,” he said.

“As it only affects SA, it would mean the Federal Government is making a conscious decision to strip funds from our state while every other state retains the status quo. This is grossly unfair and will hit our rural and remote roads program hard.”

“If cut, it would have the effect of funding SA local roads at about $240 less per kilometre than in other States.”

“It would be completely unfair,” he said.

Mayor O'Loughlin said the LGA had raised the issue before last year's Federal Election, individually with relevant Federal Ministers, in a delegation to Canberra in March this year, with SA Liberal MPs and with the SA Premier and Leader of the Opposition.

Federal authorities could hardly be made more aware, but O'Loughlin is still calling on SA’s federal minister to keep the topic alive.

“More recently almost every SA Council has written to their Federal MP to make sure all MPs understand the issue and are working in SA's interests. We have made no secret this is a top order issue for our local communities,” he said.

“I understand governments need to make tough financial decisions but to make South Australians bear more than their fair share is unacceptable.”

Mayor O'Loughlin said SA had lost millions of dollars of funding over more than 15 years before the supplementary fund was introduced, and it was disappointing that neither Coalition nor Labor governments had fixed the underlying problem despite two reviews over 10 years and clear commitments to do so.