Australia has been found to exercise the most care in handling dangerous weapons such as usable nuclear materials, beating 32 other nations in nuclear materials security.

The United States, whose president two years ago called for international cooperation to keep potentially damaging material and weapons from falling into the wrong hands, made only 13th place, tied with Belgium.

The three countries with the highest rankings were Australia (94 out of 100), Hungary (89) and the Czech Republic (87), followed by Switzerland, Netherlands, Sweden, Poland, Norway and Canada, Germany and United Kingdom tying at 10th place.

The report, conducted by U.S.-based non-governmental organization Nuclear Threat Initiative, was released Wednesday after a yearlong scrutiny of the involved countries, suggesting many still have far to go.

"If terrorists succeeded in blowing up a large city somewhere in the world, the result would be catastrophic... human toll of hundreds of thousands dead and injured, disruptions to global commerce and global confidence, and long-term environmental and public health consequences," NTI co-chair and former U.S. Sen. Sam Nunn, D-Ga., said.

The report noted a quarter of the 32 nations studied scored poorly on social factors due to "very high levels of corruption," while several others scored poorly on foreseen "political instability over the next two years."

"Some of those sites are well-secured, many are not, leaving weapons-usable nuclear materials vulnerable to theft or sale on the black market to terrorist organizations that have publicly stated their desire to use nuclear weapons," the study said.

The five bottom countries in the list were India; Vietnam; Iran for its corruption, political instability and poor procedures for nuclear control and accounting, Pakistan for its political instability, presence of militant groups, corruption and number of storage sites; and North Korea for its lack of transparency and compliance with international standards.

The original five nuclear powers were found in mid-range, gauged because of the importance of their stockpiles as well as corruption in China and Russia - Britain 10th, the US 13th, France 19th, Russia 24th and China 27th.

Japan came in at 23rd because of its absence of an independent regulatory agency, while Israel, although it has never confirmed it is a nuclear-armed state but is regarded by the international community as holding atomic weapons, landed 25th due to lack of transparency and lax control procedures.

Researchers ranked countries based on five categories: Quantities and sites, security and control measures, global norms, domestic commitments and capacity, and societal factors.

The NTI's nuclear materials security index attempts to generate global benchmarks to note countries' progress in securing highly enriched uranium and plutonium stored in hundreds of localities worldwide.

The NTI released the report in conjunction to a global nuclear summit to be held in Seoul, South Korea, in March. The study recommended building a foundation for a global nuclear materials security system and improving state stewardship of nuclear materials.

"There is greater know-how today to build a bomb, and there are terrorist organizations determined to get the material and build a weapon if they can," Nunn said. "It is clear that the elements of a perfect storm are gathering. There's a large supply of plutonium and highly enriched uranium and what we call weapons-usable nuclear materials."