Hornsby-Ku-Ring-Gai Hospital is investigating a woman's claims that staff coerced her into handing over her baby for adoption after giving birth there in the 1960s.

A hospital spokesman said they had received a letter from Janice Kashin last Wednesday.

"An investigation has begun into the circumstances she described while a patient at the hospital in 1963," they said.

"Ms Kashin is being contacted by hospital staff to assure her that we will keep her informed of the progress of our investigation.

"While the hospital management will do its best to investigate this matter and any matter of patient care that is brought to its attention, the length of time - 46 years - that has elapsed in this case may make it difficult to determine the actions of staff at that time.

"Hornsby Hospital does not condone the practice of coerced adoption and would unhesitatingly apologise to any woman who may have experienced that in years past."

A number of women have spoken out over the weekend about the need for a Senate inquiry into what they have dubbed "Australia's secret stolen generation".

They say thousands of single women were forced to hand them over for adoption in the '60s and '70s after giving birth in hospitals.