The Delhi Jal Board (DJB) was on Tuesday taken to task over construction of a sewage treatment plant by the National Green Tribunal which warned its officials not to play a "smart game" on the issue concerning pollution in river Yamuna.

"For the past one-and-a-half years, we are grappling with this problem which has been generated by your client (DJB). Tell your officers not to play smart game with us. This is causing us lot of concern. Your client is causing suspicion," a bench headed by NGT Chairperson Justice Swatanter Kumar told the counsel appearing for DJB.

The bench was irked that it was not informed earlier that the sewage treatment plant (STP) at Delhi Gate drain was not working properly.

"Why we were not told about all this? This is very unfair. Should the tribunal rely on you (DJB)? You have frustrated the tribunal. We went out of the way to help the DJB but everytime DJB is found to be wrong," the bench said.

Senior counsel H S Phoolka, who appeared for DJB, told the NGT that when this STP was constructed, it was not anticipated that it would have so much load. He also said that flow of waste water would be diverted to other STPs.

The bench, however, directed DJB to furnish details about work covered under phase one of their projects and also budget expenditure plans by May 9, the next date of hearing. The tribunal on Monday had come down heavily on DJB over construction of the STP at Delhi Gate drain here and had also directed it to provide details of planned expenditure in the current fiscal with regard to water and sewage sector.

The bench is monitoring the implementation of its 'Maili se Nirmal Yamuna Revitalisation Project'. In order to keep the Yamuna river clean, DJB had last year started trial run of its newly constructed 15 MGD waste water treatment plant at Delhi Gate Nalla.

According to the DJB, the plant, which is odourless and functions on clean fuel, has been constructed at a cost of Rs 204 crore. The waste water treatment plant aims to tap highly polluted water from old Delhi areas.

The tribunal had earlier rapped DJB for spending money on Yamuna without its permission and had directed it not to spend a "single penny" on rejuvenation of river without its nod. It had also directed DJB not to surrender the amount allocated to it in the last fiscal for rejuvenation of Yamuna to the Delhi government and asked it to spend the funds for implementation of its 'Maili se Nirmal Yamuna Revitalisation Project'.