Doubts are emerging about Australia's plans to export uranium to India even before the prime ministers of the two countries meet to discuss the Cabinet's decision in favour of the yellowcake shipment.

Foreign Minister Alexander Downer warned on Wednesday that no uranium would be exported to India until the conclusion of the agreement between the US and India on nuclear power.

On Tuesday, the national security committee of Cabinet decided in principle to export uranium to the subcontinental nuclear power, conditional on agreed safeguards.

Downer said Australia would "first of all" have to await the signing of a US-India pact to transfer civilian nuclear fuel and technology before Australian uranium went to India, The Australian reported on Thursday.

The US State Department on Wednesday warned that an Indian atomic test could sabotage the deal, as Pakistan continued to complain about uranium shipments to its nuclear rival.

In Canberra, the opposition Labour Party demanded the Coalition immediately review the pending decision to sell the uranium to India.

"The Indian government won't rule out nuclear testing and Australia has multiple international treaty obligations that the government should uphold," Opposition foreign affairs spokesman Robert McClelland said.

Australia is a signatory to the Nuclear Non-Proliferation Treaty, whereas India is not. Its refusal to sign up to the agreement has intensified fears that uranium for Indian power plants could be diverted for military purposes.

"We now have a government of Australia pulling the rug out from under the NPT and saying we don't need to observe it any more," Kevin Rudd said.

McClelland said Labour, if elected, would overturn any decision to sell uranium to India and would lobby as a member of a nuclear supplier's group to block such exports.

Downer, however, told the ABC on Wednesday night Australia could have its own and International Atomic Energy Agency inspectors checking Indian nuclear plants to ensure proper use of the uranium if the exports eventuate.

"This will provide still more safeguards than we currently have," he said.

For the decision to move beyond the Cabinet room, however, John Howard would need to start talks with Indian Prime Minister Manmohan Singh [Images] on the steps required before exports could take place.

Dr Singh's statement to Parliament on Monday that the US-India deal "does not in any way affect India's right to undertake future nuclear tests, if it is necessary" is unlikely to reassure its neighbour.