US President George W Bush will sign legislation opening a potentially lucrative nuclear trade with India on Wednesday, a week after the deal was ratified by the US Congress, the White House said on Monday.

The pact will provide India access to US nuclear fuel, reactors and technology, overturning a three-decade ban on such trade. The ban was instituted in 1974 when India first tested nuclear weapons.

Before it can take effect, Bush will have to certify that the pact is consistent with the nuclear Non-Proliferation Treaty as well as that it is US policy to work with others to restrict the further transfer of equipment and technology for uranium enrichment and reprocessing spent nuclear fuel.

India and the United States will also exchange diplomatic notes to put into effect the agreement, ratified by the US Senate last week and the House of Representatives last month.

US Secretary of State Condoleezza Rice was in New Delhi last week in hopes of signing the pact but she was not able to because administrative procedures had not been completed by the United States.

The India-US deal could open up around $27 billion in investment in 18 to 20 nuclear plants in India over the next 15 years, according to the Confederation of Indian Industry.