The Transport and General Workers' Union is demanding statutory equal pay audits after figures released this week show the gender pay gap is not closing.
Female brokers earn half that of their male counterparts, while women in manual jobs earn £117.20 a week less than men carrying out the same duties, according to the 2002 New Earnings Survey.
The Office of National Statistics report shows that female manufacturing staff earn just £251 a week, compared with £368.20 for male colleagues.
"We need commitment on the part of employers to conduct equal pay audits to root out where inequalities lie," said Diana Holland, national organiser for women race and equalities at the T&G.
"But there are still some employers who are not prepared to close the gender pay gap voluntarily. We need statutory pay audits. Responsibility rests with the
Government to strengthen the equal pay laws and to encourage employers in every industry to support equal pay audits.
"It is high time employers and the Government get real on equal pay and close the gender pay gap - we have waited long enough."