The Delhi High Court on Wednesday questioned the city government's proposal to use Rs 400 crore out of the Rs 700 crore Environment Compensation Charge (ECC) fund to purchase 500 electric buses.

"Why do you (Delhi government) want to use the just discovered ECC funds for buses? Buses are a part of essential functioning of government. Plan to purchase buses has been pending for a long time," asked a division bench of Justice S. Ravindra Bhat and Justice Sanjeev Sachdeva.

"Why divert environment funds for bus purchase?" the bench asked, after the Delhi government told it that government has planned to purchase 500 electronic buses from the environment fund as a measure to curb air pollution in the national capital.

The government also told the court that a part of environment fund would also be used for creating charging infrastructure and for procuring 1,000 CNG propelled standard low floor buses by DTC, and another 1,000 such buses would be procured and engaged under cluster scheme.

The court also asked the government to inform it on December 14 the five important steps which the high-level committee, formed by the government, will take to control pollution along with a timeline and how it proposes to implement it.

Earlier, the court had asked the city government, Central Pollution Control Board (CPCB) and the Delhi Pollution Control Committee (DPCC) to apprise it of how it intends to spend money collected as green cess and other similar funds to mitigate air pollution in Delhi.

The court was earlier informed that over Rs 700 crore had been collected as green cess for bringing to Delhi cars of 2000cc or larger engine capacity.

The court was hearing a suo motu case it initiated in 2015 to control air pollution in the national capital.