Emergency services were called to Shortland Esplanade at Newcastle Beach in Newcastle around 4.35am today following reports of a missing swimmer.

Police were told an unknown woman had entered the water about 10 minutes earlier and had not returned to the shore.

Police officers, Marine Area Command, Marine Rescue and a Westpac Rescue helicopter have been engaged in a multi-agency search for the missing woman.

She was last seen wearing a pink top, black pants and no shoes.

Marine Rescue NSW Inspector Courtney Greenslade said a rescue vessel with volunteer crew was deployed before sunrise to search for the missing woman.

“Marine Rescue Newcastle volunteers will continue to assist NSW Police Marine Area Command until instructed otherwise,” Greenslade said.

“Conditions are favourable offshore this morning, with seas under a metre and a 10-knot east to north-easterly wind.”

Anyone with information is urged to contact police or Crime Stoppers on 1800 333 000.