The drivers of the vehicles furnished with seat belts must drive the vehicle with fastened seat belts, and has no right to carry the passengers without the fastened seat belts.

However, the law provides exceptions from the rule:
It is allowed to carry children under 12 years without the fastened seat belts (except for the cases of compulsory fastenings the seat belts provided by the law), as well as the instructors may not fasten the saet belts when the vehicle is driven by the trainee. In addition to these in the settlements the drivers and passengers of the vehicles of operative services, as well as of the vehicles with special colored signs may drive or be in the vehicles without the fastened seat belts.

Source: Iravaban.net