The draft accord allowing the United States to provide atomic technology and fuel to India will still require a final nod by the leaders of the two countries, the officials say.
"The agreement has been finalized but it awaits review by both governments," Rahul Chhabra, the spokesman for the Indian embassy, says.
The talks were led by US Under Secretary of State Nicholas Burns and Indian Foreign Secretary Shivshankar Menon.
"The discussions were constructive and positive, and both Under Secretary Burns and Foreign Secretary Menon are pleased with the substantial progress made on the outstanding issues in the 123 agreement," a joint statement says.
"We will now refer the issue to our governments for final review," the statement says.
The implementation agreement, or "123 agreement," is intended to capture all operational aspects of the nuclear deal, which was agreed upon by US President George W. Bush and Indian Prime Minister Manmohan Singh two years ago to highlight strategic ties between the world's two biggest democracies.
After government approval, the pact will have to be cleared by the Democratic-controlled US Congress, where lawmakers have vowed tight scrutiny.
The US Congress already approved the nuclear deal in principle last year and a bill to that effect was signed into law by Mr Bush.
But the law requires a comprehensive implementation agreement that has to be approved again by the Democratic-controlled Congress.
India also needs to sign an additional protocol with the International Atomic Energy Agency and get the approval of the 45-nation Nuclear Suppliers Group.
Overturning 30 years of sanctions
The deal would reverse three decades of US sanctions imposed over nuclear tests carried out by India, which is not a member of the Nuclear Non-Proliferation Treaty.
The United States and India "look forward to the completion of these remaining steps and to the conclusion of this historic initiative," says the joint statement.
The deal could open up a whopping 100 billion dollars in opportunities for American businesses, according to the US Chamber of Commerce.
For the nuclear deal to be implemented, India should separate nuclear facilities for civilian and military use and set up a regime of international inspections to allay concerns that material and technology received are not diverted to boost its nuclear weapons arsenal.
Despite several rounds of talks, India has stood fast against accepting any curbs on its reprocessing of spent nuclear fuel.
India also wants assurances that Washington will continue to supply fuel for its atomic plants in the event New Delhi conducts further nuclear weapons tests.