The United States has made it clear that the civil nuclear energy cooperation deal with India will be "terminated" if New Delhi conducts an atomic test.

India has been maintaining that the 123 Agreement is silent on the issue of testing. Prime Minister Manmohan Singh [Images] told Parliament on Monday that the agreement to operationalise the civilian nuclear deal will not affect India's right to undertake future nuclear tests.

"Let me hence reiterate once again that a decision to undertake future nuclear test would be our sovereign decision, one that rests solely with the government," Dr Singh said.

"The proposed 123 Agreement has provisions in it that in an event of a nuclear test by India, then all nuclear cooperation is terminated," US State Department Spokesman Sean McCormack said on Tuesday.

The spokesman also said there is "provision for return of all materials, including reprocessed material covered by the agreement."