The post-mortem of India's failure to sign the Teesta water sharing treaty with Bangladesh during Indian Prime Minister Manmohan Singh's visit has begun.

The pact was all ready to be signed during Manmohan's 30-hour trip to Dhaka that ended on Wednesday. But it fell through at the last moment because of objection from Paschimbanga Chief Minister Mamata Banerjee. New Delhi said Mamata was duly consulted about the pact.

The collapse of the water treaty almost eclipsed the other gains the two countries achieved from the high-profile visit. This is because the Teesta deal was the most coveted trophy Bangladesh had wanted, according to analysts.

Manmohan said Mamata's last-minute opposition to the deal took him by surprise.

“I was told all the technicalities were setded but in the meantime something obviously happened, and Mamataji disagreed with it," the prime minister told Indian journalists accompanying him aboard a special plane taking him back to New Delhi onWednesday.

He also provided some details of his steps to finalise the draft of the deal.

"I sent National Security Adviser Shiv Shankar Menon to talk to Mamataji a long time ago. He met her in Kolkata and then he also undertook a mission to Dhaka," Manmohan said.

“But some other factors came into play, and she (Mamata) said she won't come. It is only then, I realised about disagreement with regard to the Teesta,” he said.

He further said when the Teesta treaty issue had come up before the cabinet committee on political affairs a few days prior to his trip to Dhaka, Railway Minister and Mamata's party colleague Dinesh TYivedi raised objections to it

Manmohan sent his national security adviser to Mamata again, he said, explaining his efforts to get Mamata's nod to the deal.

He admitted he may have made a mistake.

“One learns from one's mistake. I'm not claiming that I'm infallible,” said Manmohan who will turn 79 on Sept. 26.

He said he will continue to work with Mamata and will take into account the interests ofWest Bengal.

That means Mamata and her Paschimbanga have now emerged as a deciding factor in the water sharing deal. The Indian leaders are now indicating that a fresh beginning

will be needed in reaching a consensus on the Teesta pact. It is now more important to get Mamata to agree to any deal struck by Dhaka and New Delhi on sharing the Teesta water.

Manmohan is in no mood to upset Mamata, whose Trinamool Congress is a pow-erful partner in the Congress-led United Democratic Front central government.

Asked if Mamata was responsible for India's diplomatic embarrassment over the Teesta, Manmohan evaded a direct reply, saying, “Mamataji is one of our key political leaders."

Meanwhile, officials in Dhaka are trying hard to keep their cool despite a general public disappointment over the Teesta failure. A further delay in resolving the Teesta dispute will mean further loss in the multi-million taka Teesta irrigation project.

At a media briefing about the Indian PM's visit, Foreign Secretary Mijarul Quayes said New Delhi is committed to signingthe Teesta agreement. “We are hopefill of an agreement within next few months,” he said on Wednesday, echoing the optimism expressed a day earlier by Finance Minister AMAMuhith.

The Teesta debacle prompted Dhaka to pull out from the hoped-for deals on the Feni river, and allowing India to use Chittagong and Mongla ports and transport goods through Bangladesh territory.

In spite of the failures, Manmohan described his maiden bilateral visit to Bangladesh as “very satisfying" and said it would have been more successful had the Teesta agreement been signed.

Meanwhile, Manmohan said he returned from his visit to Bangladesh with the impression that all political parties in that country are willing to work with New Delhi to strengthen bilateral relations.