As the United Progressive Alliance government came under Left pressure for putting on hold implementation of India-United States civil nuclear deal for six months, the United States on Tuesday night said time is of the essence to take the last steps in operationalising the agreement.

"The US Congress must vote once more on the 123 Agreement, an action best accomplished by this administration in the life of this Congress," US Ambassador David C. Mulford said addressing the fourth Indo-US Economic Summit organised by the Indo-American Chamber of Commerce.

He said completing the IAEA safeguards agreement and securing changes in Nuclear Suppliers Group will enable India to pioneer a new era to meet its energy needs.

"Now, we must take the last steps. Time is of essence," he said at the summit attended by Montek Singh Ahluwalia, Deputy Chairman of the Planning Commission.

Mulford's remarks came on a day when CPI-M asked the government not to operationalise the deal for at least the next six months.

Mulford said the steps involved "completing the International Atomic Energy Agency safeguards agreement and securing the NSG rule change which will permit this initiative to be global in its scope".

Finalisation of the India-specific safeguards agreement and changes in NSG guidelines are required for operationalising the deal.

He also said taking the final steps in implementation of the deal would end India's nuclear isolation.

"The bottom line here is that when these final steps are taken, India's isolation in the global civil nuclear field will end," Mulford said.

Mulford said the nuclear deal will enable India to launch its new large-scale industry and pioneer a new era to meet its energy needs that will ultimately benefit all its people.

"We are at a great moment in the history of our two democracies. We have overcome past differences and charting a new course for the future," he said.

The new course in the Indo-US ties involves a comprehensive relationship that touches all fields of human endeavour of which the civil nuclear is "only one part of the larger whole," Mulford said.

"We are engaging with India on virtually every important front, from defence and space cooperation to critical transnational issues such as counter-terrorism, health, education and climate change," he said.

Mulford noted that the burgeoning business collaboration between the two countries are based on the foundation of India's economic reforms over the past 15 years.

While American investment in India has grown to nearly USD 900 million in the current financial year, he said the US has been one of the largest recipients of Indian investment, roughly to one-fifth of its total investments abroad.

Mulford said the central and state governments have not been able to adequately fund or disburse public investment in agriculture resulting in stagnation or decline in farm production in the last decade.

Noting that leading Indian companies plan to invest billions of dollars in organised retail, Mulford said "this level and diversity of investment is far beyond the means of the government alone to provide and, if forthcoming, will bring about significant improvements in both job opportunities and quality of life in rural areas.