COMMUNITIES in the Western Isles will have to wait up to four years beyond the original target date for their fragile economy to be transformed by green energy production.

As many as 3500 jobs depend on the success of wind, wave and tidal projects in the area over the next two decades.

But now it has emerged that a £750million transmission interconnector cable to carry all the extra power to the mainland may not be ready until 2019.

Scottish Hydro Electric Transmission has written to developers behind renewables projects on the Western Isles asking them to confirm that they plan to take forward their schemes.

It follows confirmation that they will be able to sell their electricity at £115 per megawatt hour (MWh), the strike price, compared to £90/MWh on the mainland. The strike price is a minimum price that will be paid, with the Government paying the difference if the market rate falls below it.

The Western Isles had sought a strike price closer to the offshore price of £130.

But the power company, which is part of energy giant SSE, says it needs these assurances before approaching the regulator Ofgem with a business case for the cost of the interconnector.

David Gardner, SSE's director of transmission said: "We have been working on the case for a link to the Western Isles for around 10 years.

"A significant amount of work has been undertaken by UK and Scottish governments, the regulator and others to address the concerns raised since the developers withdrew in 2010 and the confirmation of the strike price has provided further clarity.

"For us to make progress through the regulatory approval process, which is designed to safeguard the interests of customers, we are seeking written confirmation from developers that their projects are viable."

Mr Gardner said that as a result the estimated completion date for the interconnector has been pushed back to 2019. Previously 2015 and then 2017 had been the dates targeted. He said the new date "factors in" Ofgem approval which can take at least 15 months and the cable's manufacture time of 18 months.

Local council leader Angus Campbell said islanders had been campaigning for 12 years for the cable.

He said that the "delay has been totally unacceptable," adding: "Whilst it is possible that the interconnector will be put back to 2019 our understanding is that is a worst case scenario and we would hope that it can happen earlier.

"We would hope that after all this time Ofgem would give this a level of priority it deserves to hopefully speed up the process and allow an earlier ordering of the cable."

Mr Campbell, along with Orkney and Shetland councils, have agreed with Energy Minister Fergus Ewing to hold a summit in the new year with the UK Government and power firms following the strike price announcement by the Department for Energy and Climate Change.

Mr Ewing added that the summit would provide an opportunity to help developers if they are unhappy with the strike price, which could be different for each island group.