The SNP want to set up a trust fund with oil revenues

The party published an economic policy document at its annual conference in Perth which lists proposals for a wealthier Scotland.

It claims a new trust fund from the proceeds of North Sea oil would give Scotland an extra �4.3bn each year.

Delegates backed plans to introduce direct elections to NHS boards.

On the second day of the conference, members also voted to tackle under-age drinking and to raise the legal age for smoking from 16 to 18.

Later, the SNP pledged to replace the Forth Road Bridge, either with a new bridge or a tunnel.

Two of the economic measures - cutting corporation tax to 20%, or 10% below the UK level, and the creation of an oil fund - would have to wait for full independence.

We need a focus on Scottish economic growth that London can't and won't deliver Stewart Hosie SNP treasury spokesman

The party argues that if corporation tax is cut in Northern Ireland, as demanded by some politicians in the province, Scotland could follow suit.

The other measures, including the business rates pledge, could all be achieved by an SNP administration within the present set-up.

The party proposes to abolish business rates completely for all businesses with a rateable value of �8,000 or less.

These currently number 120,000.

A further 30,000 small firms would have their rate bills cut, with 50% rates relief for firms with a rateable value of �8,000 to �10,000, and 25% relief for firms with a rateable value of �10,000 to 15,000.

'Scottish economic growth'

The party argues that the cost of low growth in the last two years alone has been a �2bn shortfall in the economy, equivalent to �400 for each member of the population.

The party argues that cutting corporation tax below UK levels would grow the economy and increase tax revenues by �10bn over 10 years.

Stewart Hosie, the SNP's treasury spokesman, said: "The lesson from Ireland, and Norway, Finland, Sweden, Denmark, Iceland, all nations richer per head than the UK, is that we need a focus on Scottish economic growth that London can't and won't deliver."

Meanwhile delegates voted for at least 50% of health board places to be elected.