Check all the lines to and from the petrol tank for proper connections and tightness.
If the smell still persists, check all lines in the engine bay.
If the problem still persists, check the tank cap for a proper seal.
Having excluded these possibilities, it may be that the car as sold in the Pakistan market does not have an Evaporative Emissions Control system, in which case, you may be out of luck.
Please note that long term exposure to petrol fumes, in a closed space such as a car, even in low concnetrations, can cause health problems, from headaches (simple) to anemia (bad) to leukemia (not so simple). Children are more at risk for these complications.