It looked like it was struck hard so the vessel didn't come outside after the initial attempts. The troubleshooter in me said that - "Know the problem well before you attempt to fix it". So I decided to take all the water out and see what is blocking.. Once we drained we figured out that the we were trying to take the portion of the sink itself and not the obstructing vessel.
If we had continued we would have damaged the sink itself. And once we isolated the problem we could just take the small vessel using hand and no sophisticated weapon or method is required.. So, the lesson learnt..
Know Your Problem well enough before you attempt to fix! :-)