"Around Rs 800 crore is lying with you (DJB) from the budget. Anything in excess of Rs 50 crore you won't spend without prior approval of the tribunal and till the judgment is passed on the issue," a bench headed by NGT chairperson Swatanter Kumar said.

The green panel, which is monitoring the "Maili Se Nirmal Yamuna" project, made the observation while hearing a bunch of pleas alleging encroachment of river bed, floodplains, pollution and illegal sand mining on river Yamuna.

The bench expressed surprise over DJB's annual budget of over Rs 1,400 crore and said till the order is passed on the pleas, it should not spend more than Rs 50 crore.

The panel reserved its verdict on the pleas after it was alleged that despite the budget, untreated sewage is being discharged into Yamuna.

The bench asked DJB to explain how much money it has spent on construction of sewage network and sewage treatment plants (STPs).

To this, the DJB counsel said that till March 31, 2015, more than Rs 900 crore has been spent on the construction of sewage lines, sewage treatment plants and interceptors.

The bench then asked DJB what was the cost on cleaning of river Yamuna before 2005 and how much fund it has got from the Centre.

The Tribunal had yesterday banned the sand mining on Yamuna after a plea alleged that some private firms were engaged in the activity and a temporary bridge was built on the river obstructing its na tural flow of water.

It had said that no mining activity, both legal and illegal should be carried out on the banks of river Yamuna till the next date of hearing.

The panel had appointed a local commissioner and a representative of the Ministry of Environment and Forest to file their joint inspection report on sand mining on either side of Yamuna at Gautam Budh Nagar in Uttar Pradesh and Fari dabad in Haryana.