The North Delhi Municipal Corporation must phase out its old diesel trucks before planning to buy new ones, the National Green Tribunal (NGT) said here on Thursday. Disposing off a petition by NDMC seeking permission to purchase new diesel trucks, an NGT bench headed by Justice Swatanter Kumar said: “First phase out nine old diesel trucks, then buy the new ones.” The NDMC had sought the tribunal’s permission to buy 10 new diesel trucks, worth Rs 1 crore 32 lakh, while asserting that it faced problems with garbage collection and transportation using older trucks.