Congress' Union Ministers from Karnataka S M Krishna, Mallikarjun Kharge and K H Muniyappa and 16 Bharatiya Janata Party MPs from the state, led by M Venkaiah Naidu, met Singh separately on Tuesday seeking a review of the CRA decision.
"Both the groups sought a stay. The PM told them that it is not permissible as there is no mechanism under CRA to change its award...it is not the decision of the PM but of the CRA. The CRA will have to meet again for any such thing," Water Resources Minister Pawan Kumar Bansal, who was present in both the meetings, told the media in New Delhi.
Later, speaking to reporters, Karnataka Chief Minister Jagdish Shettar said the state would file a review petition before the CRA on Tuesday and demanded that Singh take up the issue immediately.
"The Cauvery case came up in the Supreme Court on Tuesday. Our counsel said the state is not in a position to release any water (to Tamil Nadu). This is the stand of the government. We will meet the PM on Tuesday and file a review petition (of the CRA order)," he said.
On September 19, the CRA had directed Karnataka to release 9000 cusecs of water to Tamil Nadu daily between September 20 and October 15.
Shettar's comments came as the apex court on Monday said its order directing Karnataka to supply 9,000 cusecs of water to Tamil Nadu will not be an impediment in the PM deciding on the review petition.
Bansal said quoting the PM that the Centre will act keeping in mind the interests of both the states.
The CRA is chaired by the PM and comprises chief ministers of Karnataka, Tamil Nadu, Pudducherry and Kerala, besides the water resources minister.
The Cauvery Monitoring Committee, comprising the Union water resources secretary and chief secretaries of the four states, will meet here on October 11 to decide on the release of water by Karnataka after October 15.
"The CMC will decide on the issue in consultations with the states. If it fails, the issue may be referred back to CRA...yes, CRA could be convened again in such a scenario," Bansal said.
He refused to comment on whether the authority meeting could be convened before October 15, saying no date has been fixed.
"If there is a qualitative change in the situation following the onset of northeast monsoon in Tamil Nadu, the matter could end there," he said.
Bansal said that based on flow from Karnataka, which varied from 4000 cusecs to 13,000 cusecs on different days, Tamil Nadu has received 1.21 lakh cusecs of water as against 1.44 lakh cusecs between September 20 and October 5. He has circulated the data to the leaders who met Prime Minister Manmohan Singh on Tuesday.
He said besides the 65 tmc (thousand million cubic feet) of water available in Karnataka's main reservoirs, another 60 tmc of water was available in canals. He said while the southwest monsoon has withdrawn, Tamil Nadu will get rains from the northeast monsoon shortly.
Both Tamil Nadu and Karnataka have moved the Supreme Court against the CRA award. While Tamil Nadu has demanded more water, Karnataka has claimed that it is not in a position to release more water from Cauvery river to the neighbouring state.
While Karnataka has said its standing crops are under threat, Tamil Nadu has claimed that its first crop has failed and seedlings of its "samba" or second crop will die due to lack of water.