Highlands and Islands MSP Donald Cameron, the newly-appointed opposition health spokesman, hit out during questions with government health minister Jeane Freeman at Holyrood.
It follows a newspaper investigation which found that at least 37 hospital patients which had tested positive for Covid-19 were discharged by Scottish health boards into care homes between March 1 and April 21.
NHS Highland, which covers Argyll and Bute, has so far neither confirmed nor denied whether it was among them.
It did not answer a Freedom of Information request in time and this week it explained that the information requested had taken 'longer than anticipated'.
A spokesperson told The Oban Times that it was compiling its response and plans to share it 'as soon as possible'.
Jeane Freeman, MSP for Carrick, Cumnock and Doon Valley, told the debate that it was 'entirely wrong' to suggest that sending covid patients into care homes was a government decision.
Such decisions were made by clinicians with risk assessments followed and conversations and co-operation with care homes, she explained.
Since the start of the pandemic, guidance on the discharge and admission to care homes had also 'evolved,' she added. The current guidance tried to ensure that patients who are at risk are not transferred 'inappropriately,' she said.
Ms Freeman added: 'Any individual who is being placed in a care home must be subject to an appropriate risk assessment and be isolated for 14 days.'
Ms Freeman has now asked Public Health Scotland to work with health boards to produce 'validated statistics and analysis' on the number of patients who tested positive for Covid-19 and were subsequently admitted to care homes.
'That includes examining how many were assessed as being discharged when they were considered to be infectious, and the rationales that were in place for such a discharge, for example in the case of palliative care concerns,' said Ms Freeman.
Mr Cameron said it had 'taken months' for parliament and the Scottish public to learn the news which had never been addressed by the First Minister in daily briefings.
Mr Cameron said: 'We heard about those appalling mistakes — mistakes that possibly cost lives — only because of a newspaper investigation, which did not even include responses from every health board in Scotland.
'I am afraid that the cabinet secretary’s answers are wholly unacceptable. Nearly 2,000 people have died in care homes in Scotland from coronavirus — every single one of them an unspeakable tragedy.'
Ms Freeman said the Crown Office was looking at deaths in care homes and would investigate where appropriate.
She said: 'There can be no doubt that I and this Government take very seriously the situation in our care homes, but I hope that, equally, there is no doubt that we have, at all times, acted with the best of intention and based on the information that was available at the time.'
Officially, 46 per cent of all Scotland's confirmed coronavirus deaths occurred in care homes, while there have been 3,833 of confirmed cases among care home residents.
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