Proposed wind farm projects in the Northern and Western Isles could be the only onshore projects in Scotland to be unaffected by the UK Government's recently announced plans to scale back subsidies for the sector, it has emerged.

Scotland's onshore wind sector - which claims that £3 billion of investment is now under threat - had been hoping that a statement in the House of Commons by energy secretary Amber Rudd on Monday would clarify how many proposed wind farm projects in Scotland would qualify for transitional support after Rudd earlier this month announced the government would bring forward the qualifying date for support under the Renewables Obligation Contract (ROC) scheme by one year, from March 2017 to March 2016.

This would mean that any onshore wind project completed after that date would instead have to apply for support under the less generous Contracts for Difference (CfD) subsidy scheme. But last week, Rudd hinted that the government was also considering closing the CfD scheme to onshore wind.

Although Rudd said that the Department for Energy and Climate Change (DECC) would implement a "grace period" for projects which meet three specific conditions (having planning permission, ownership of land or a lease and the installation of a grid connection) there is continuing confusion over whether the qualifying date of 18th June for the meeting the first two conditions would also apply to the third.

Confusion over the government's plans was compounded last week when Scottish Secretary David Mundell told the BBC that the grace period would apply "when there is any prospect of a grid connection being delivered".

The confusion over funding for the sector has led the Scottish government to announce it would hold an emergency summit to discuss the impact of the UK Government's decision early next month.

In an interview on BBC Radio Scotland Rudd said she planned to discuss support for "the small islands" with Scottish energy minister Fergus Ewing at a meeting on Wednesday, but a spokesperson for DECC later declined to comment on what she said were "private talks" between the two ministers.

Although none of the wind farm projects planned for the Western and Northern Isles would have been built in time to qualify for support under the ROC scheme, when it comes to support under the more strictly rationed and competitive CfD scheme the government has indicated that onshore wind farms on the Scottish islands will be considered as if they were offshore wind projects, for which there is a separate funding pot.

Niall Stuart, chief executive of Scottish Renewables, told the Sunday Herald: "The Secretary of State's continued support for the islands projects has been one of the very few positives for the industry over recent weeks, but I think nothing can be taken for granted until the proposed arrangements for funding remote island projects under the CfD scheme are signed off by the European Commission and formally launched by the UK Government."