Staff gathered outside the main entrance in protest

Nurses and medical secretaries were among those who stood outside the main entrance for 15 minutes before returning to work.

They said management had not done enough to cool down the hospital, which was built using the Private Finance Initiative and opened in January.

Most of the staff said that temperatures in the building had soared in recent weeks but that they had been complaining about the problem for months.

One told BBC Scotland: "We cannot work in this. We're suffering from heat exhaustion and everything.

"We want something done now, we can't wait any longer."

Further inquiries

But Jane Todd, site manager at the new hospital, insisted everything possible was being done to solve the problem.

She said: "There are a number of areas where there are consistently high temperatures and these require to be further investigated.

"It has been exacerbated by the temperatures outside in the last few weeks.

"I appreciate it's a very difficult time for a number of staff who are having to work in difficult conditions, but we are trying to seek solutions as quickly as possible."

Scotland's heatwave is said to be cooling off with weather experts predicting showers over the next few days.

Temperatures are not expected to rise above 21C.