Prospect has written to universities and science minister David Willetts raising concerns about a massive cut in funding to a key organisation that represents the interests of women in science.
The union's head of research Sue Ferns urged the minister to reconsider its withdrawal of funding for the UK Resource Centre for Women in Science, Engineering and Technology.
"As a union we are acutely aware of the under-representation of women in SET functions and industries, and of the valuable role played by UKRC in encouraging young women to take up SET careers as well as in supporting women returners," the letter said.
"As the government's own analysis demonstrates, these skills are key to returning the UK economy to high-quality growth and in stimulating and sustaining the green economy. Yet, despite the demand for such skills, there is no evidence to show that the SET labour market is yet able to address the challenges of women's under-representation without support from expert practitioner bodies, such as UKRC."
Prospect has around 50,000 members working in science and engineering in a diverse range of functions and disciplines, ranging from animal health to forensic science and from climate change research to nuclear physics.
Ferns said that Prospect had worked with UKRC over an extended period and believed it was a lean and efficient organisation that consistently delivered. While it has a good track record in attracting project-based funding "this is not a substitute for the core funding that is required to maintain capability and key over-arching functions, including provision of labour market intelligence and awareness raising."
Since the letter was sent the government has offered the UKRC £500,000 of transition funding for one year. Ferns said, however, that this still represents an 80% cut in the organisation and does not resolve issues of long-term sustainability.