By Lin Taylor

LONDON (Thomson Reuters Foundation) - More than half of British women have been sexually harassed at work, according to a survey published on Wednesday, but almost 80 percent said they did not report the incident to their employer.

Nearly one in five respondents said the perpetrator was their direct supervisor, and around a quarter said they felt they would not be taken seriously or believed if they reported the harassment.

Young women between 18 and 24 fared worse than other age groups, with two-thirds experiencing workplace sexual harassment, according to the report by the Trades Union Congress (TUC) and women's rights group Everyday Sexism.

"The numbers are shocking and it should be a wake up-call," Alice Hood, head of equality at TUC told the Thomson Reuters Foundation. "Sexual harassment is still a really big problem for women in the workplace. It's certainly not gone away."

She said many women did not report the incident because they were embarrassed, thought they would not be taken seriously, or feared it would damage career prospects.

Sexual harassment can include sexual jokes or innuendos, the circulation of pornography, inappropriate touching or unwanted sexual advances, according to the report, which surveyed 1,533 women across Britain aged between 18 and 65.

Almost a third of women said they had been the subject of sexual jokes at work, and one quarter said they had experienced unwanted touching, such as on the knee or lower back.

"Things have not improved anywhere near as much as people would like to think," said Laura Bates, founder of Everyday Sexism.

"It's so pervasive because it isn't being talked about. Women don't feel they are able to come forward, and when they do, it isn't being dealt with at all."

Hood said employers must confront and deal with harassment through staff training, changing workplace culture and by implementing robust policies.

"Maybe it's happening on email or social media - but it's still harassment and it still has a really humiliating effect on people experiencing it," she added.

"Employers need to do much more - it is clearly a huge problem. The first step is taking it seriously ... so people know that harassment won't be tolerated."

(Reporting by Lin Taylor @linnytayls, Editing by Emma Batha.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters that covers humanitarian issues, conflicts, global land and property rights, modern slavery and human trafficking, women's rights, and climate change. Visit http://news.trust.org to see more stories)