Trade body Scottish Care said the impact of the virus on residents alongside staff absence levels of up to 30% had put homes under huge strain.

There have been concerns over the number of deaths and adequate protective equipment at care homes.

Fears have also been raised over a "postcode lottery" when it comes to testing care workers and residents.

Scottish Care's members provide the vast majority of Scotland's 36,000 care home beds, with chief executive Dr Donald Macaskill saying the virus had left the sector facing an "unprecedented challenge on every front".

The outbreak has killed several residents at care homes in Dumbarton, North Lanarkshire and Tranent in recent weeks.

And information gathered by Scottish Care from its members suggests that about half of care homes in Scotland have at least one suspected case of coronavirus.

Dr Macaskill said concerns about deaths in homes were understandable, but had to be seen in context and treated with caution.

He said: "80% of people in care homes are there for later stage of life care. It is a place where there are, sadly, frequents deaths and we have seen that older people generally are more vulnerable to the virus."

Why are there no official figures?

There is an official count of the number of suspected cases of coronavirus in care homes, but it could be up to three months before it is published.

The Care Inspectorate has asked all care homes to notify them when they have a suspected coronavirus case or when a resident dies from the virus, and to keep them updated on staff shortages.

However, the taxpayer-funded watchdog is refusing to publish this Scotland-wide data at the height of the crisis.

Instead, BBC Scotland has been told its request for the data is being treated as a freedom of information request, which under the emergency coronavirus laws means the Care Inspectorate has three months to respond.

The watchdog says it is because of concerns over the "robustness of the data" coming from care homes.

Despite these concerns, the same data is being given to councils, health boards and the Scottish government to help them "deliver support across partnership areas and nationally".

Robert Kilgour, owner of Renaissance Care, which has 14 care homes across Scotland and around 1,100 staff, said he has suspected coronavirus cases in about half of his facilities.

The firm has had three confirmed cases, two of which were where people died, but "without access to proper testing" he is unsure of the full extent of the virus among staff and residents.

He said: "Testing feels like a big issue right now but our experience is there is a postcode lottery where testing in some areas of the country is good and in others it is non-existent.

"Times are tough, the NHS is so vitally important but we have to remember a collapse in social care sector would also spell disaster for the health service."

Mr Kilgour said his business was operating with an absence rate of about 15%, but those who were able to come to work were excelling.

He explained: "The response from staff has been nothing short of amazing, a proper Dunkirk spirit.

"For many of them the residents and their colleagues are like a second family and they are pushing on for them.

"I've had reports of a number of staff moving into the care homes to protect their own families and allow them to keep working."

The Scottish government has issued new guidance on the personal protective equipment to be worn by care workers and health boards have been asked to prioritise testing to enable health and social care staff to get back to work.

Health Secretary Jeane Freeman has said protecting staff working on the frontline is "an absolute priority" for the Scottish government.

What does the lockdown mean for residents?

Experts have warned that the virus has left many care home residents struggling to cope with the collapse of their social networks.

Family visits and activities at the majority of homes have been suspended, with many residents also being isolated in their rooms as a precaution against the virus.

Prof Adam Gordon, of the British Geriatrics Society, who specialises in how healthcare is delivered in care homes, said: "We have to remember a care home is a community so a resident might have social relationships with other residents, the staff and of course family visiting.

"Overnight this routine has gone or severely disrupted.

"So for people who have any sort of memory problem it is a really tough time right now, especially if they might not have much understanding of the wider world.

"We know loneliness and social isolation can result in worse outcomes for older people and it is a real concern given how long the lockdown is likely to last."

Scottish government figures show about 60% of adults in care homes have some form of dementia and Dr Macaskill, of Scottish Care, said the lockdown measures were having a "profound impact" on both residents and stretched staff members trying to keep their spirits up.

He said: "People just need to just think about how their own lives have been impacted and then consider the disruption to routine it is having for someone in a care home, perhaps with dementia."

One bright spot has been a Scottish Care drive to increase the use of tablet or mobile phone devices to connect residents with friends or families.

"We've had some wonderful donations of equipment. It is not for everyone, but there have been many heart-warming examples of staff using technology to try and bridge this gap," Dr Macaskill explained.