Two sketches have been released by police of a man thought to have sexually assaulted up to 27 women in Sydney’s eastern suburbs over a 16-year period.

Sydney detectives said they established Task Force Doreen and began investigating five sexual assaults in the city’s eastern suburbs in 2000.

But when the cold cases were reviewed, they expanded the investigation to include 27 other incidents of attempted or actual sexual assault.

Officers said every case was linked by a combination of DNA and a similarity in the way the attacks were carried out.

A DNA profile has been sent interstate and internationally, but no match has been found so far, they have said.

The suspect targeted women, with victims aged between 14 and 55, commonly threatening them with a knife.

Police said every incident was thoroughly investigated at the time it was reported, but despite numerous appeals over the years for information, all have remained unsolved.

Officers have released two identikit sketches of the man and are appealing for potential witnesses who lived in the area between 1984 and 2001 to come forward.

They believe the man would now be aged between 45 and 64 and describe him as being about 160cm-180cm tall with a dark complexion, dark wavy hair, brown eyes and a broad nose.

His physique would have changed over time with him having a thin build when the assaults first started, but in the 1990s he was described as being of an athletic or muscular build.

He spoke with an Australian accent and kept his face covered on all occasions, wearing hooded jumpers.

It is believed no more assaults were committed after 2001.