The International Atomic Energy Agency said it will loan Brazil selected types of radiation detection devices, including personal radiation detectors, for the Games in August and September.
The Vienna-based IAEA is also prepared to provide and/or facilitate assistance to Brazil "in the event of a nuclear or radiological emergency," it said in a statement.
A corresponding agreement was signed today in Rio de Janeiro by Renato Machado Cotta, Brazil's nuclear chief, and Khammar Mrabit, director of the IAEA's Division of Nuclear Security.
Experts and politicians have long warned of the risks of extremists getting hold of nuclear materials. US President Barack Obama last week hosted a summit on the subject in Washington.