Union Haddiema Maghqudin Secretary General Josef Vella was told to leave his mobile before being allowed to enter the Home Ministry for a meeting with Minister Karmenu Abela.
Mr Vella refused and the meeting was put off.
In a statement revealing this, Mr Vella said he has never been treated like this, not even for meetings with the prime minister at Castille.
This is not the way to treat social partners, Mr Vella said, adding this attitude shows lack of trust in UHM by the government.