The General Workers' Union has accused the ministry responsible for health of discriminating between ambulance drivers of the same rank and said it would not stop industrial action until the situation changed.

Last week, the union ordered ambulance drivers to provide reduced services.

A union spokesman said ambulance drivers at Mater Dei Hospital were working under better conditions than those at Guardamangia. This included the way shifts were assigned and things such as food allowances.

The union was also protesting against the transfer of a supervisor who it insisted was "carrying out his job". It accused the health authorities of using other workers as strike breakers by hiring transport using taxpayers' money.

The GWU said that while it expressed solidarity with patients and relatives affected by the industrial action it had no alternative to proceed until a just solution was found.