Ergonomics
The leading association for international efforts in ergonomics is the IEA:
The International Ergonomics Association
The IEA stitches federated societies from all over the world with the aim to 'advance ergonomics science and practice' and thus 'improve the quality of life throughout the world.
They do so through their affiliation with theWorld Health Organization (WHO), the International Labour Organization (ILO), the International Occupational Hygiene Association (IOHA) and the International Commission on Occupational Health (ICOH).
Collectively, they improve occupational health and safety at national, international & global levels. (see agreement here or here)
Usability
Although usability has not been made as concrete and globally organized as ergonomics, there are some organizations that make international efforts to coordinate the methods and outcomes of applying usability:
As the name suggests, HFI is an international organization that has made as much an effort as the BCPE in promoting standardized practices in human factors; focusing primarily on software usability. However, as of December 2008, nearly 70% of their certified members reside in the United States, suggesting that HFI's reach is not yet as international as it could one day become.
(For a complete breakdown of CUA member nationality as of December 2008, click here)
International Standards Organization
The ISO, offers four international standards (two product oriented and two process oriented) on how to define and conduct usability assessments.
ISO 9126: A Model of Software Quality
ISO 14598: Documenting Usability Tests
ISO 13407: Human-Centered Design
ISO 9241: The Ergonomics of Human System Interaction + usability heuristics & measures
In order to establish these standards ISO used a workgroup of their software engineers comprised of experts from around the world. Most of the standards have been evolving since the early 1990s.
International Usability Partners
The IUP is comprised of eight partnered companies representing China, Finland, France, Germany, Italy, Spain, the United Kingdom and the United States with a network that extends to an additional nineteen other countries.
Each partner company operates strictly under the user-centered design approach set out by the International Standards Organization (ISO 13407).
Although the IUP is primarily a coalition of companies rather than governmental organizations, they do collect and provide free guidelines on how to practice usability, thus reassuring clients of each IUP-partnered company that their professionals are qualified and competent.
Education-wise the IUP largely focuses on methods of participant recruitment.