The green panel also questioned Delhi government's odd-even formula for vehicles to check pollution in the national capital, saying it may not achieve the desired purpose.
"In view of serious contribution of vehicular pollution to air quality of NCT Delhi, it is important that the government should take a serious view and a decision whether any diesel vehicle, old or new, should be registered in Delhi.
The Tribunal directed Centre and state governments to consider not to buy any diesel vehicles for their departments.
Casting doubts over the Delhi government's ambitious plan, the panel said that that the odd-even formula for vehicles may "encourage" people to buy two cars.
On April 7, the green panel had held that all diesel vehicles which are more than 10 years old would not be permitted to ply in Delhi-NCR.
Earlier, the bench in November last year had banned all vehicles which were more than 15 years old and held that they would not be permitted to ply on the city roads.
