The transported Department has stopped issuing fitness certificates to retrofitted CNG buses since yesterday. This means that diesel buses which have installed CNG kits will not be allowed to ply in the Capital. The decision comes in the wake of the Supreme Court order asking the Department to take converted buses that don't meet safety norms, off the road from August 5. The Department had last week filed an application in Court seeking three-month's time to check all the existing converted buses and maintained that "prima facie it appears as though all the buses are meeting safety norms."