A hospital trust has written to striking staff urging them to return to work before patients are affected.

Almost 400 administrative and clerical workers in Glasgow walked out on Thursday over pay and regrading issues.

Glasgow NHS Trust criticised the walk-out as an apparent disregard for patients' welfare.

Unison, the health union, urged its members to stop the unofficial action - and said a nationwide deal on pay would be offered next week.

The strike affects Glasgow Royal Infirmary, the Royal Maternity Hospital, Stobhill and Canniesburn Hospitals, and the Dental Hospital.

Workers want better pay and conditions

A spokeswoman for the trust said the strike would not affect patients this weekend - but could disrupt care if it continued.

There are no talks planned until Monday.

Tim Davison, trust chief executive, said: "Without these staff, we will be unable to sustain all our services.

"It will be necessary to prioritise and concentrate our efforts on treating emergencies and other critical care patients.

"There is a real danger therefore that continued unofficial action could result in elective, planned patients being cancelled."

Joe Di Paola, Unison's Scottish organiser, said: "Unison simply doesn't understand why this action is being taken now instead of waiting for a Scottish-wide offer on low pay to be made next week.

"It is doubly perplexing given the procedure for the branch to get a ballot for official action has already started."

One Royal Infirmary employee said staff felt they had been backed into a corner.

Health Minister Malcolm Chisholm has urged staff to end their strike and return to work.