Covid-19 cases in an outbreak on Barra in the Western Isles have increased to 39.
NHS Western Isles has described the situation on the island as "serious" and "escalating".
On Sunday, the health board said there had been 12 new positive tests related to the Barra outbreak, which first emerged more than a week ago.
Separately, two new cases were also identified in a smaller outbreak on Benbecula.
The total of four Benbecula cases include a member of the US defence services who had arrived on the island for a naval ballistic missile defence exercise at the Hebrides Range, a military rocket firing facility.
The US Missile Defence Agency said all US and UK Covid protocols were followed.
On Barra, those who have tested positive along with more than 100 close contacts are self-solating. The number in isolation represents about a 10th of the island's total population.
'Let guard down'
In the Scottish government's Covid briefing on Monday, Chief Medical Officer Dr Gregor Smith said he and First Minister Nicola Sturgeon had held "preliminary discussions" on how to "limit and contain" the spread of the infection.
He said the matter would be examined further by ministers ahead of the Scottish government's weekly update on restrictions on Tuesday.
Dr Smith suggested people socialising had led to the outbreak, which the government was monitoring "very closely".
He said: "What we are seeing in Barra is a good example of what happens when people let their guard down and come together."
Barra and Vatersay Covid-19 Forum said the majority of islanders were self-isolating, including people who had not been asked to do so.
Chairwoman Marion MacNeil said Barra had in effect gone into a "voluntary lockdown".
She said the communities of Barra and neighbouring Vatersay had "remarkable resilience" and islanders were doing everything possible to support one another.
NHS Western Isles has appealed to islanders to be vigilant for symptoms of Covid-19 and to self-isolate immediately and arrange a test if they believe they have the infection.
People have also been warned of the potential risk of using items of high levels of contact, such as a cash machine, and to sanitise their hands before and after use.
The health board added: "We would remind individuals to avoid regular trips to the supermarket and keep shopping trips to a minimum and as necessary.
"Shop alone, wear a mask at all times and hand sanitise before and after shopping.
"Respect other shoppers and shop workers by ensuring you maintain a two metre distance from others at all times."