The remark by a bench of Justice Arun Mishra and Justice Deepak Gupta came when it was told that the project is "critical" and the pending issues should be resolved soon.
Amicus curiae and senior advocate Aparajita Singh told the bench that the Environment Pollution Control Authority (EPCA), in its report, said that the project has been held up since 2014, when it was submitted to the Centre for its approval.
The project is designed to join the current network and make the system more viable and attractive to commuters, the advocate said.
The EPCA report has pointed out a stalemate in the discussions between the Central and the Delhi governments due to different financial aspects of the project.
The Delhi government has said that Delhi Metro would not start work of Phase-IV till the issues related to bearing of the operational loss, repayment of the Japan International Cooperation Agency's loan, sharing of land cost and taxes and others are resolved.
The Centre told the bench that funding for the project has been done as per the Metro Rail Policy of August 2017.
The court asked the government counsel to take instruction from the authority concerned on the issues regarding the cost of land and liability of taxes among the Centre and state government on the project.
The amicus also told the court about remote sensing technology which can be effective to check emission of particulate matter (PM) and other hazardous substances.
The court was hearing a matter related to air pollution.
( With inputs from IANS )