Safety concerns have been raised about the handling of radioactive waste at a Scottish nuclear plant.

The Nuclear Decommissioning Authority says safety has "deteriorated" at Dounreay and warned improvements made after a fire in 2014 have not been kept up.

Environmental protection agency Sepa rated the handling of waste last year as 'at risk' and called the management of vaults used to store it 'poor'.

There were three serious incidents at the 60-year-old plant in Caithness, where decommissioning work has been under way since the 1990s.

They included workers dropping a glovebox - a device used to store leftover coolant - which caused the release of radioactive contaminants.

A radioactive fuel assembly was also dropped but nobody was injured in either incident.

The Scottish Government has called for urgent action to address the problems at Dounreay, which were revealed in the NDA's latest annual report.

Environment secretary Roseanna Cunningham has written to UK energy minister Richard Harrington.

"There continues to be cause for concern in Dounreay's environmental performance, with Sepa having to take action," she said.

"In addition, the recently published NDA annual report presented in stark terms the lack of progress at Dounreay across a wide range of projects.

"While I am aware that the exotics movement programme has been a priority this is still a disappointing state of affairs and sits oddly with the planned reduction in workforce at Dounreay."

About 200 jobs are expected to be cut at Dounreay, about 15% of the total workforce.

Ms Cunningham noted: "Local stakeholders have told me that they cannot understand why the current substantial voluntary redundancy programme is in place where there is still so much work to complete on the site."

The cost of decommissioning Dounreay has risen by around £50m in the last two years to £2.32bn, partly as a result of the need for an extension to a waste store.

"It is vital that there is continued momentum in the safe and effective clean up at Dounreay," Mr Cunningham added. "The people of the north of Scotland deserve nothing less."

Gail Ross, SNP MSP for Caithness, Sutherland and Ross, also said she was "seriously concerned" about Dounreay's safety record.

However, the plant's environmental performance has increased overall over the last year, according to the NDA, which said it was "disappointed" by the problems but saw "signs of recovery".

An NDA spokesman said: "Decommissioning and hazard reduction at Dounreay remain a priority for the NDA and the contractors performing the work.

"We will respond directly to Ms Cunningham about the points she raises in her letter."