The Council of Trade Unions says the Government has embarrassed itself internationally by voting against measures to help protect workers around the world.
At a conference of the International Labour Organisation (ILO) in Geneva, more than 160 countries have been debating setting international standards for the employment of domestic workers.
CTU president Helen Kelly, who was at the conference, says other countries were shocked to find out New Zealand wouldn't support the convention.
Ms Kelly says it was a bad move for the Government to have cast a no vote. Most nations have given their backing, she says, and that will improve working conditions for vulnerable people.