The European Court of Justice (ECJ) will ruled on Tuesday that an employer can prohibit staff from wearing the Islamic headscarf or other religious symbols in the first case of its kind before the EU's top court.

"An internal rule of an undertaking which prohibits the visible wearing of any political, philosophical or religious sign does not constitute direct discrimination," the Luxembourg-based court said.

The ECJ ruled on the cases of two female employees in Belgium and in France, who were dismissed for refusing to remove their headscarves, a day before a Dutch parliamentary election dominated by the issue of immigration and integration.

The court's ruling considered the case of a Belgian woman working as a receptionist for G4S Secure Solutions, which has a general ban on wearing visible religious or political symbols.

The court's advocate general last year recommended that companies should be allowed to prohibit headscarves as long as a general ban on other symbols was in place. Companies should though consider the conspicuousness of such symbols and the nature of the employee's activities.

The court's ruling will also cover a French IT consultant who was told to remove her headscarf after a client complained.

The advocate general's advice in the French case was that a rule banning employees from wearing religious symbols when in contact with customers was discrimination, particularly when it only applied to Islamic headscarves.

An opinion of an advocate general is not binding but is followed by the court in the majority of cases.