President Obama's speech on nuclear disarmament in Prague is an open invitation for Australia to reduce the role of nuclear weapons in our own security policy, according to the Australian Greens.

"While Australia remains under the US nuclear umbrella, our country is giving legitimacy to these genocidal weapons and credence to the idea that they bring security," said the Greens Nuclear Spokesperson, Senator Scott Ludlam.

"Obama's decision to immediately and aggressively pursue US ratification of the Comprehensive Test Ban Treaty is welcome news for Australia, as it was Australia that put this on the agenda by taking it to the Treaty UN General Assembly back in the 1990s."

"It's also encouraging to see a new international effort to secure all vulnerable nuclear material around the world within four years. Australia should take a lead in supporting this initiative, by cleaning up its act at home."

"Loose nuclear materials turned up last week in a police raid in Victoria, which reveals inadequate material control procedures and a disturbing deficiency in workplace culture in the responsible handling of uranium."

Senator Ludlam has tabled questions on notice on the uranium finding last week.