AN SNP plan to cap onshore wind-farm developments would cause Scotland to fail key renewable energy targets and see investors leaving the sector, according to industry leaders.

Leader Alex Salmond would cap onshore developments to appease objectors if he becomes first minister in May. But industry leaders say his plans to boost offshore instead won't work.

Salmond said: "There is a real difficulty with public acceptance of onshore wind. There should be a cap on future developments. We should concentrate the development of onshore wind into suitable areas."

Salmond said financial support for onshore wind farms should be looked at again as he believed there was a danger onshore wind developers were getting too much financial support.

He added: "Onshore has an extremely good deal fiscally at the moment. Emerging technologies should be fairly treated. The vast potential of offshore has to be opened up."

Jason Ormiston, acting chief executive at green energy trade body Scottish Renewables, said: "A significant wave and tidal stream industry will not be with us until the next decade. With the ever worsening prognosis on climate change, what do we do in the meantime?"

He added: "Scotland has a comparative advantage in onshore wind and any attempts to stop good projects would undermineconfidenceinaclean energy policy that sought to reduce carbon emissions as quickly as possible and in Scotland's ability to deliver emerging technologies."

And Nicol Stephen, Liberal Democrat deputy enterprise minister, said: "This is a shameless U-turn. It blows away the SNP's green policies. By imposing a blanket policy like this he will shatter the confidence of investors.

"This will threaten the future of wave and tidal projects as well as wind. We have made huge progress to our target of 18% of electricity from green sources. The SNP would stop it in its tracks."

Onshore wind-farm developers have long expressed fears that their sector would become a political football and that investment would suffer as a result.

There have already been a number of changes to the regulatory system of support and the sector believes more changes could put off investors. Developers have expressed fears of offshore wind being used as an excuse to halt deployment of future onshore farms.

Alan Baker, Airtricity Scotland CEO, said he was nervous of any attempt to boost offshore wind farms before the technology is in place. He said: "Offshore wind is a reality in England where coastal waters are shallower. In Scotland we have deep water offshore and the technology is not there yet."

Ormiston added: "A good energy policy embraces a number of technologies to ensure secure, affordable supplies of electricity and promote new technologies. The entire renewable electricity industry would therefore be very concerned if there was an attempt to unnecessarily restrict onshore wind."