A Melbourne practice has apologised after accidentally injecting up to 30 patients with saline instead of the Pfizer COVID-19 vaccine.

In a statement released on its website on Friday, the Deepdene Surgery said the mistake occurred when empty vials were inadvertently mixed in with unused vaccine vials before being diluted with saline.

This meant that some doses drawn up and administered to patients contained saline only.

“As a result, 30 people may or may not have received Pfizer but only an injection of saline,” the statement from the practice said.