THE Scottish Office yesterday unveiled what it termed the ''biggest change in decades'' to the way in which industry is lured to areas of high unemployment through regional selective assistance.

Industry Minister Brian Wilson announced extra grants of up to #3000 for each new job created in five needy areas and said that if the experiment proved successful in Scotland, it would be copied throughout the United Kingdom.

Mr Wilson said the new ideas were designed to replace the so-called ''trickle-down'' theories of the previous government which had clearly failed areas of high unemployment and social deprivation.

Companies both at home and from abroad which invest in the five areas will not only have their regional selective assistance (RSA) increased, but will be able to draw from New Deal money, childcare spending and a fund for training employees hired locally. The short-term target is to create 2000 jobs.

The scheme, called RSA Priority, will be piloted in a large area across the north of Glasgow and the city's East End, West Dunbartonshire, Dundee, and the Three Towns of North Ayrshire (Ardrossan, Salcoats and Stevenston).

At the same time, the Government's Property-Employment Support Programme (Pesp), which encourages investment in industrial and commercial property in deprived areas, will be spread to include parts of Paisley, Cambuslang, and Rutherglen along with the Three Towns plus Glengarnock, Motherwell, and Wishaw, Hawick, Glasgow's Drumchapel, Gorbals, greater Pollok and Govan, and south-east Alloa. Other designations will

follow.

The minister described RSA Priority as a radical, ground-breaking effort to make it attractive to invest and expand in areas of high unemployment using a local workforce.

''It recognises the need to get work back into the hearts of communities which have been hardest hit by unemployment,'' he said.

''It should be of major assistance to economic development agencies in attracting investment to these areas, and in encouraging existing businesses to expand.

''I will be watching progress of the scheme very closely. If it succeeds there is the prospect of it being extended to other communities with similar problems.''

The Scottish Office has put up to #7m aside for the scheme which will be assessed after a year. It is aimed mainly at smaller businesses but Mr Wilson made clear that if a major investor arrived on the scene offering hundreds of jobs ''we would hardly be likely to tell them to go away because the budget had run out''.

Ardrossan and Salcoats, which are in Mr Wilson's constituency of Cunninghame North, qualify for assistance in both the RSA Priority and Pesp schemes. He made clear they had been selected only because they qualified under guidelines involving unemployment levels and other socio-economic factors.

All of the areas involved have unemployment at double the Scottish average of 7.1%. In Ayrshire's Three Towns there are local areas where male unemployment is 25%, Mr Wilson said.

''This Government means business in attacking the root causes of deprivation and bringing opportunities to all Scots.

''These uniquely Scottish initiatives will play a key role in combating social exclusion by providing access to work for some of those communities worst affected by unemployment.''

Jim Torrance, Scottish policy convener of the Federation of Small Businesses, welcomed the change and said anything which helped small business expansion was good news.

qMr Wilson later visited Ardrossan in Ayrshire, heart of the Three Town's unemployment black spot which the new initiative is designed to help, writes David Steele.

He said: ''There are pockets of unemployment in this area as high as 25% and this is a totally unacceptable level.

''If we are to tackle unemployment properly then clearly we must attract jobs. I believe that an initiative of this kind is the best way to do that.''

He added: ''This area has been slowly devastated by the rundown of ICI and other important industries and we must now try to redress the balance.

''It may be that local companies will find Priority RSA attractive or it may be that new firms will be drawn to the area.

''In any event there is a determination to improve the employment situation in Ardrossan, Saltcoats and Stevenston in the coming year.''

Councillor David Munn, vice chair of infrastructure and environment on North Ayrshire Council, said: ''This is excellent news coming so close behind the announcement that further European cash is to come to the Three Towns.

''What we face in this area is not only the blight of unemployment but the reduction in confidence and self-esteem which comes with it.

''I believe that this dual approach will assist enormously in moving things forward. It will allow us as a local authority, in conjunction with the local enterprise company, to offer real incentives to local companies and to inward investors to create jobs.''