Chief secretary Rajiva Sinha on Friday asked officials of several departments and police to “show results” of the crackdown on 15-year-old vehicles instead of exchanging data or making plans to curb movement of such vehicles, sources said.

Sinha wanted to know how many owners have been prosecuted for plying vehicles older than 15 years or more or how many of them have been sent notices, asking them withdraw such vehicles, sources said.

“Show me results. Give me prosecution figures,” Sinha was quoted by an official as saying at the meeting. “Have we been successful in stopping these vehicles from plying?”

Senior officials of the urban development, environment and transport departments and pollution control board were present at the meeting convened to take stock of the measures taken so far.

Bengal will have to present its case before a bench of the National Green Tribunal on December 16. Officials of several departments submitted a combined report that said enforcing the 15-year-old ban would “immediately affect” over nine lakh petrol-driven vehicles, of which over four lakh would be cars.