We have been working for more than two years in a company with unlimited contract. Our contract states that the working hours per day are 8 hours. Last month the company informed us that we have to work 1 hour a day as an overtime but without extra payment  and the company informed everyone about that and anyone who objects will be fired from the company.
Our question is, as per the labour law do we have the rights not to obey our company order working overtime without payment? Do they have the rights to terminate our contract if we will not follow their new order regarding the working hours overtime without payment?

I would like to clarify to the questioner that the UAE Labour Law, article 65 states the following: “The maximum normal hours of work of adult workers shall be eight a day or 48 a week. The hours of work may be increased to nine hours a day in commercial establishments, hotels and cafes and of guard duties and any other operations where such increase is authorized by order of the Minister of Labour and social affairs. The daily hours of work may be reduced in the case of arduous or unhealthy operations by order of the Minister of Labour and social affairs.
The normal hours of work shall be reduced by two during the month of Ramadan.
The periods spent by a worker in traveling between home and place of work shall not be included in his hours of work”. Therefore, the employer has violated the above article and therefore if the employer refused to pay the overtime hours, the questioners shall file complaint before the Ministry of Labour in this regard. If the employer terminates the employment contract, he will be in breach of the employment contract.