SA Libs promise regional roads upgrade

Mining royalties will be used to upgrade regional roads across South Australia if the Liberals win the state election in March.

Thirty per cent of royalties worth $750 million would be set aside to fund roads over the next decade, Opposition Leader Steven Marshall says.

"We want to make sure that the regions across South Australia are going to get their fair share of infrastructure money to upgrade critical roads," he told ABC radio on Wednesday.

SA's peak transport group welcomed the move but said Mr Marshall needed to clarify if the money was in addition to current funding.

"If this is on top of current funding, it is a great outcome," SA Freight Council spokesman Evan Knapp said.

However, the Labor government said the plan would actually mean a cut to road spending.

With projected mining royalties worth $251 million this year only about $75 million would be spent on regional roads under the Liberal plan, Transport Minister Stephen Mullighan said.

Mr Mullighan said the government had already promised to spend more than $90 million.

"This Liberal policy is a real slap in the face to the South Australia's regions," he said.