Police are investigating a robbery of 49-year-old woman overnight in the Hunter overnight.

At around 8pm on Sunday evening the woman was approached by a man while walking her dog.

He threatened her and demanded money before she handed over her mobile phone and ran from the man onto Lancaster Street.

The woman knocked on the doors of nearby homes until a resident helped her call police.

The man is described as being of Aboriginal/Torres Strait Islander appearance, about 175cm tall, with a thin build, and less than 20-years of age.

Anyone with information is urged to contact crimestoppers.