GENEVA, Oct. 29 (Xinhua) -- The salaries of self-employed doctors in Switzerland are around a third higher than previously thought, according to a study released on Monday by the Federal Office of Public Health.

"The incomes of doctors in Switzerland are significantly higher than the previous analyzes suggested," the study said.

The study showed that independent specialists received an annual median income of 257,000 Swiss francs (257,000 U.S. dollars).

However, certain specialists can earn considerably more such as neurosurgeons, who take home a median salary of 697,000 Swiss francs and gastroenterologists of 627,000 Swiss francs.

Oncologists, anesthetists, maxillofacial surgeons and radiologists all earn more than 500,000 Swiss francs, said the report.

It said the median figure marks the point at which half the doctors make more money and the other half make less. It can be a more effective measure than the average, which is distorted by extremely high salaries.

The self-employed medical specialists who earn the least are psychiatrists and psychotherapists for adults who earned some 195,000 Swiss francs and those for children, 183,000 Swiss francs.

General practitioners, who provide primary health care, are paid a median salary of 237,000 Swiss francs.

A total of 118 doctors were found to earn more than 1 million Swiss francs, although this is probably an underestimate, the authors said.

The study is based on income subject to old-age insurance from 2009-2014 of almost 8,000 self-employed doctors.

It also shows that female medical professionals systematically earn less than their male counterparts. The income gap, allowing for experience and discipline, is 29 percent said the report.

Previous studies had been carried out into salaries of self-employed medical professionals, but these were criticized for methodological weaknesses.

For example, the increasing proportion of part-time work had not been factored in and the number of doctors assessed was small.