"... we want to see this agreement concluded. We think it's in the best interests of India, the United States, as well as in global nonproliferation efforts. But, as you know, we've acknowledged that there are internal political issues for the Indian government to work out, and it's important that they have an opportunity to do so," State Department's Deputy Spokesman Tom Casey told reporters.

He was asked whether the "now or never" warning by US lawmakers was due to an "urgency" in the two countries to finalise the nuclear agreement.

"US lawmakers, members of Congress, speak for themselves. They have a very important role to play in this process. But when they are abroad, they are speaking in their own name as members of our legislative branch," Casey said.

The senior State Department official added that the US wanted to see the agreement "concluded as quickly as possible".

"But ultimately, the Indian government needs to be fully comfortable with it and they need to be able to do move things forward," Casey said.