The new members ranged from Kazakhstan to Poland, Jordan and Ghana. Almost two-dozen nations were present as potential candidates or observers including Canada, Libya, Turkey, South Korea, Britain and other large EU states.

The GNEP aims over the next few decades to commission proliferation-resistant nuclear reactors with assured international supply of fuel, curbing dependence on oil and gas, fuels blamed for greenhouse gases triggering climate change.

Washington said the GNEP was not directed against suspected nuclear proliferators like Iran, which says it is enriching uranium only for electricity not bombs, and would not require developing states to renounce fuel production on their own soil.

But US Energy Secretary Samuel Bodman said that while the GNEP was "not an exclusive club", only nations with a clean non-proliferation record could take part under its covenant.

"It is an equal and voluntary partnership open to all nations who ... agree to international accepted standards for a safe, peaceful and secure nuclear fuel cycle," he told the start of a GNEP ministerial meeting.

Global demand for electricity is forecast to almost double by 2030 and rise by 150 percent in developing countries. Only nuclear energy could satisfy this development pressure without jeopardising the environment, GNEP proponents said.

NATIONAL SOVEREIGNTY CONCERNS

The UN nuclear watchdog chief welcomed GNEP in part because it did not seem to undermine national sovereignty on energy, a concern that has hampered various proposals for a more secure multilateral system of atomic energy supply in the past.

"This has been one of the issues that has created a lot of anxiety ... So this is very much an improvement and should encourage more countries to join the partnership," International Atomic Energy Agency Director Mohamed ElBaradei said.

But South Africa, a major developing nation invited to the ceremony, did not show up, reflecting lingering fears the GNEP could lead to certain technology restrictions, diplomats said.

ElBaradei told the meeting that much remained to be done to get the GNEP off the ground.

He said a major challenge would be developing commercially feasible nuclear reactors with fuel-recycling and waste disposal minimising the risk of yielding plutonium usable for bombs.

After the ceremony ministers held closed talks on creating a GNEP organisation that would attract more countries, hatch new technology projects and establish sources of funding.

"GNEP is a way to share the promise of atomic energy without the attendant risks of weapons proliferation since new entrants to the nuclear market would have no need to produce their own enriched uranium or dispose of nuclear waste in ways that might give them weapons-usable plutonium," said Mark Fitzpatrick of the International Institute for Strategic Studies.