Can we attain liberation by asana practice?

This is not possible as we deal with the body with hatha yoga (even though we may use our entire consciousness in executing the pose). We are still at the level of matter by perfect asana practice. To reach that transcendental state we have to change deep within- we need trikarana shuddhi- integrity of thought word and deed. Nothing else. In this state compassion exists and purity leads to divinity. We may be a perfect executor of asnas but if we lack human qualities it does not have any meaning. Asanas are only a stepping stone- they are not the goal.