The Scottish government has officially requested support from the military to deal with pressure in the ambulance service that has extended waiting times, the Ministry of Defence has confirmed.

On Thursday, Nicola Sturgeon told MSPs during first minister’s questions the possibility of asking for aid was “under active consideration”, but the request came just a few hours later.

The MoD has said the request related to support of the mobile testing units deployed by the Scottish ambulance service, which would free up resources within the service.

Sturgeon apologised to people who had endure long waits for ambulances, including the family of 65-year-old Gerald Brown, the Glasgow man who died after waiting 40 hours for treatment.

A spokeswoman for the MoD said: “The Ministry of Defence has received a request from Scottish government under the military aid to civilian authority process. We are working hard to identify where we can most effectively assist other government departments and civil authorities.”

A Scottish government spokesperson said: “As the first minister set out, targeted military assistance for the Scottish ambulance service is being requested.

“This support is being sought to address acute services. In addition, a separate request has been submitted for military assistance to support staffing of mobile testing units (MTUs) to help them run at increased capacity.”

Speaking in Holyrood earlier, the first minister said: “I apologise unreservedly to anyone that has suffered or is suffering unacceptably long waits.

“Military assistance is already being provided to ambulance services in England, and of course we have had military assistance for other aspects of the pandemic over the past 18 months.”

The health secretary, Humza Yousaf, who said on Wednesday that people should “think twice” before calling for an ambulance, will make a statement to parliament next week setting out measures being taken by the Scottish government to ease the crisis.

The Conservative leader, Douglas Ross, criticised Yousaf’s comments, calling them “dangerous and reckless”, and urged Sturgeon to apologise on Yousaf’s behalf – which she did not.

Instead, the first minister said people should “never hesitate in calling an ambulance if that is the intervention they think is required”.

Ross said: “This shouldn’t be happening in Scotland in 2021 … Last week, the first minister wouldn’t accept the ambulance service is in crisis. Surely the last seven days will have changed her mind?”

Sturgeon refused to say there was a crisis, instead saying: “I don’t challenge the extent of the pressure that’s on our ambulance service and indeed on all parts of our national health service.”

Pressure because of coronavirus, Sturgeon said, was driving the problems being seen in the sector. She added: “The fact that anyone in our country waits an unacceptable period of time for an ambulance when they need urgent care is not acceptable to me and it’s not acceptable to anyone, and that is why we will work closely and intensively with the ambulance service to support it to meet those challenges, which I would expect to continue for a period as the Covid pressure continues and as we go into the winter months.”

She continued: “I do not, in any way, underestimate the extent of the challenge facing the ambulance service and by extension people across Scotland.

“This is the latest in a number of significant challenges posed to us as a result of this pandemic. Our responsibility is to take the action to support the service to meet that challenge and that’s what I’m focused on, what the health secretary is focused on, and what the entire government is focused on.”

Speaking specifically about Brown’s case, a spokeswoman from the Scottish ambulance service said: “We have started an investigation into the circumstances relating to the delay in reaching Mr Brown and will be in contact with Mr Brown’s family directly to apologise for the delay in response and pass on our sincere condolences.

“We are really sorry for their loss and our thoughts are with them at this difficult time. All findings and lessons learned will be shared with Mr Brown’s family as part of the investigation process.”

Brown’s death has been reported to the procurator fiscal, who said an investigation was ongoing.