The United States and India announced Friday they have completed negotiations on a historic nuclear deal to cooperate in the development of civilian nuclear energy, an agreement designed to solidify ties between the two countries, according to dpa. US President George W Bush praised negotiators who worked through the difficult and contentious negotiations to finalize the deal signed by Bush and Indian Prime Minister Manmohan Singh in 2006. "This marks another step in the continued progress that is deepening our strategic partnership with India, a vital world leader," Bush said in a statement. US Secretary of State Condoleezza Rice and India's minister of External Affairs, Pranab Mukherjee announced that the deal had been reached in a joint statement released in Washington, but did not disclose details of the controversial accord. The agreement still must be approved by the US Congress, where it faces considerable resistance from some Democrats who complain it could compromise effort to halt the spread of nuclear technology because India has not signed the nuclear Non-Proliferation Treaty. A congressional aide told Deutsche Presse-Agentur dpa that the deal will likely not be taken up by Congress before next year. The agreement will likely go before the Indian parliament in August. India must still work out an agreement with the International Atomic Energy Agency (IAEA) to open its civilian nuclear sites to inspections as part of the deal, and must get support from the 45 countries who control the global trade of nuclear material called the Nuclear Suppliers Group. The United States and India reached a final agreement only after weeks of contentious and complex negotiations, including four days of talks in Washington last week among high level officials. The difficult part of the negotiations reportedly centred on India's demand to be allowed to reprocess US-supplied nuclear fuel and whether India will continue testing nuclear bombs. The pact has been billed as the cornerstone for strong relations between the two countries after decades of frosty Cold War relations. The United States and India have also developed tight economic and trade relations as India rises as a dominant power in South Asia. "The conclusion of negotiations on this agreement marks a major step forward in fulfilling the promise of full civil nuclear cooperation as envisioned by President George W Bush and Prime Minister Manmohan Singh," Rice and Mukherjee said in a statement, adding that it was a "historic milestone." The 123 agreement is named after a section of the US Atomic Energy Act that restricts the United States from entering into nuclear trade with non-weapons states that are not signatories of the Nuclear Non- Proliferation Act such as India unless a set of criteria is met. Under the deal, India is required to separate its civilian and military nuclear programmes in addition to meeting IAEA safeguards for US- aided nuclear facilities. The US could also demand the return of materials if the country tests nuclear weapons and a ban on reprocessing fuel that may be used for developing explosive devices. India's National security advisor MK Narayanan, asked what would happen if there was a test, said: "We will come to that later." He said the deal will not impact India's indigenous fast breeder reactor programme or any other other domestic programme. Washington slapped sanctions on India in 1998 after the country detonated a nuclear device for the first time in more than 20 years. Those sanctions were lifted after the September 11, 2001 terrorist attacks. The United States outlawed any nuclear trade with India after it first tested a bomb in 1974.