An elderly patient suffered minor bruises to his head and shoulder after a vital signs monitor mounted to the bed fell on top of him, Eastern Hospital said on Tuesday.

Two student nurses were carrying out a routine procedure when the accident happened on Monday evening, the hospital said.

A statement said the man, 70, was immediately given a check-up and scans found no fracture or other injury.

The hospital said it was very concerned about the matter and had immediately informed the patient's family.

Engineers were also sent to check all monitors of the same model on the ward to ensure safety.

"A preliminary inspection showed that the monitor concerned and the supporting mount were intact with the fixation parts functioning properly," the hospital said.

"It cannot be excluded that the monitor was not securely locked on the mounting plate."

The hospital added that it would continue a probe to find out what caused the accident.