SCOTTISH airports could benefit from an extra 100 flights a week to and from London under plans to ring-fence domestic slots on the proposed third runway at Heathrow, the UK Aviation Minister has said.

But Scottish Greens co-convenor Patrick Harvie said the plans to expand short-haul flights would “blow a hole” in the climate policies of both the Scottish and UK governments.

Protesters gathered outside Holyrood yesterday to call on the Scottish Government to change its position of supporting the third runway and to send the UK Government a message to “think again”. The plans will go before MPs on Monday.

Aviation Minister Baroness Sugg said during a visit to Glasgow Airport that the UK Government would act “if required” to reserve around 15% of new slots at Heathrow for domestic flights. She said this would guarantee connections with Scotland.

Sugg said the additional capacity would encourage competition between airlines and bring down prices for Scottish passengers. Public Service Obligations (PSOs), which exists to protect flights between UK cities, would be put in place to protect routes if required. It could also make flights cheaper, with PSOs exempt from Air Passenger Duty.

Sugg said: “I’ve just been meeting with Scottish business people who are hugely supportive and, obviously, Glasgow Airport who are too. I was in Inverness a couple of weeks ago and met with business people there who are really supportive.

“I think we’ve got great cross-party political support with the SNP being clear [in its backing] but it’s going to be down to the Scottish MPs voting on Monday, and we really want to make sure that they do vote for Heathrow.

“Although Heathrow is situated in the south east of England, the benefits of expansion will be felt throughout Scotland. We’re reserving 15% of the new slots at Heathrow for domestic use and that’s going to mean about 100 new weekly flights for Scotland.”

Harvie said: “This gives lie to the spurious claim that Heathrow expansion would simply free up slots at Scottish airports for new routes to avoid highly-polluting connection flights.

“The truth is that the plan involves a massive expansion of unnecessary short-haul flights, blowing a hole in both governments’ climate policies.

“Constructing a new runway at Heathrow is incompatible with our environmental and climate change obligations and the SNP now finds itself in a situation at Westminster where only they, the DUP and the Tories have a policy of supporting the project.”

Yesterday’s protest at the Scottish Parliament was staged by the No 3rd Runway Coalition.

Spokesman Rob Barnstone said: “Plans to expand Heathrow will be to the detriment of Scotland. The Scottish Government’s tough climate change targets would be impossible to achieve with Heathrow expansion.

“The Scottish Government shouldn’t be so trusting of the Tory Government at Westminster. Expansion at Heathrow will also impact Scottish airports, as any growth will be routed through London and not direct to international markets that could instead be served.”

International trade minister Greg Hands resigned from the UK Government yesterday to enable him to vote against the new runway.