Russia remains one of the least-safe countries in terms of nuclear security, although the country is making progress in securing its weapons-usable nuclear materials, a new report released Wednesday found.

The Nuclear Threat Initiative index — compiled jointly with the Economist Intelligence Unit — ranked Russia 24th out of the 32 countries that possess more than 1 kilogram of weapons-grade radioactive material.

The three safest countries were Australia, Hungary and the Czech Republic. The United States came in 13th place, while North Korea placed 32nd.

Russia, which possesses more than 500 tons of nuclear materials, fared poorly because of "its quantities of nuclear materials, large number of sites (which could be further consolidated) and the need for stronger regulations regarding the physical security of materials while in transit," the report said.

But despite Russia's low ranking, "today's Russia and the Russia of 20 years ago are completely different," co-chairman Sam Nunn wrote in the report, which was published on the initiative's web site.

Russian authorities have attained "significant achievements" in reducing the nuclear threat and continued their work despite considerable economic difficulties in the 1990s, Nunn added.

The report is the first of its kind to assess nuclear risks on a country-by-country basis and analyzes 176 countries in total, including a separate category of 144 states possessing less than 1 kilogram of nuclear materials.

Its aim is to help prevent nuclear terrorism and encourage governments to take actions to reduce nuclear risks. Nine hundred analysts were consulted for the index.