Important International Organisations and Groupings

Secretariat: London, United Kingdom

Members: 56 independent and equal countries.

The Commonwealth is a voluntary association spanning Africa, Asia, the Caribbean and Americas, Europe and the Pacific. Membership is not limited strictly to countries that were formerly part of the British Empire; for example, Mozambique, Rwanda, Gabon and Togo joined despite different colonial histories.

Its work includes democracy, human rights, development, rule of law, small-state advocacy and cooperation among member governments.

European Union (EU)

Principal institutional centres: Brussels, Strasbourg and Luxembourg.

Members: 27. Croatia, which joined in 2013, remains the most recent country to join the EU. The United Kingdom left the EU on 31 January 2020.

The EU is a political and economic union founded on treaties, including the Maastricht Treaty framework. It operates a single market and common legal order in areas of EU competence.

Council of Europe

Headquarters: Strasbourg, France.

Members: 46 states. It is separate from the European Union and focuses on human rights, democracy and the rule of law.

European Court of Human Rights (ECHR)

Seat: Strasbourg, France.

The Court applies the European Convention on Human Rights. It has one judge in respect of each Council of Europe member state, meaning 46 judges when all seats are filled.

EFTA Court

Seat: Luxembourg.

The EFTA Court interprets European Economic Area law for the participating EFTA/EEA states. It is not headquartered in Brussels.

Headquarters: Brussels, Belgium.

Members: 32.

NATO was founded in 1949 as a collective defence alliance under the North Atlantic Treaty. Finland joined in 2023 and Sweden became the 32nd member on 7 March 2024.

Article 5 of the North Atlantic Treaty establishes the collective-defence principle. NATO decisions are taken by consensus.

G7 Informal grouping

The G7 consists of Canada, France, Germany, Italy, Japan, the United Kingdom and the United States. The European Union also participates in G7 work. Russia participated in the former G8 format but was suspended in 2014.

The G7 has no permanent headquarters or secretariat; the presidency rotates annually.

G20 Informal forum

The G20 brings together 19 countries, the European Union and the African Union. The African Union became a permanent member in 2023.

The G20 has no permanent headquarters. Its presidency rotates, supported by a "troika" of past, current and incoming presidencies.

India hosted the G20 Leaders' Summit in New Delhi in 2023.

General Secretariat: Jeddah, Saudi Arabia.

Members: 57 states.

The OIC was established in 1969 and describes itself as the second-largest intergovernmental organisation after the United Nations. It coordinates member-state positions on matters concerning the Muslim world and broader international cooperation.

Organization of the Petroleum Exporting Countries (OPEC)

Headquarters: Vienna, Austria.

Members: 12.

OPEC was founded at the Baghdad Conference of 10-14 September 1960 by Iran, Iraq, Kuwait, Saudi Arabia and Venezuela. Its current Secretary General is Haitham Al Ghais of Kuwait, reappointed for a further three-year term from 1 August 2025.

International Energy Agency (IEA)

Headquarters: Paris, France.

Members: 32 member countries, in addition to association countries and accession candidates.

The IEA was created in 1974 and works on energy security, energy data, policy analysis and energy transitions.

Headquarters: Paris, France.

Members: 38 countries.

The OECD was founded in 1961 and develops policy analysis, standards and comparative data on economic, social, tax, governance and development issues.

Secretary-General: Mathias Cormann.

Secretariat: Beijing, China.

Members: 10 — Belarus, China, India, Iran, Kazakhstan, Kyrgyzstan, Pakistan, Russia, Tajikistan and Uzbekistan.

India and Pakistan became full members in 2017, Iran in 2023 and Belarus in 2024. The SCO works on regional security, political cooperation, connectivity, economic engagement and counter-terrorism cooperation.

As of September 2026, the SCO Secretary-General is Nurlan Yermekbayev.

Secretariat: Jakarta, Indonesia.

Founded: 8 August 1967.

Members: 11.

The current members are Brunei Darussalam, Cambodia, Indonesia, Lao PDR, Malaysia, Myanmar, the Philippines, Singapore, Thailand, Viet Nam and Timor-Leste.

Timor-Leste was formally admitted as ASEAN's 11th member state in October 2025.

Nature: political and diplomatic coordination grouping; it has no permanent secretariat or permanent headquarters.

Full members: 11 — Brazil, Russia, India, China, South Africa, Saudi Arabia, Egypt, United Arab Emirates, Ethiopia, Iran and Indonesia.

South Africa joined the original BRIC grouping in 2011. Egypt, Ethiopia, Iran, Saudi Arabia and the United Arab Emirates entered in the recent expansion process, and Indonesia became a full member in January 2025.

The New Development Bank associated with BRICS is headquartered in Shanghai, but that should not be confused with a "BRICS headquarters".

Secretariat: Kathmandu, Nepal.

Founded: 8 December 1985 in Dhaka.

Members: 8 — Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka.

SAARC seeks regional cooperation in economic, social, cultural, technical and scientific fields. Decisions are taken on the basis of unanimity, and bilateral/contentious issues are excluded from formal deliberations.

Members: India, Brazil and South Africa.

IBSA is a trilateral cooperation forum among three large democracies of the Global South. It does not have a permanent headquarters in Switzerland; coordination operates through the participating governments and rotating arrangements.

Full name: Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation.

Secretariat: Dhaka, Bangladesh.

Members: 7 — Bangladesh, Bhutan, India, Myanmar, Nepal, Sri Lanka and Thailand.

Founded: 6 June 1997.

As of 2026, the Secretary General is Indra Mani Pandey.

G5 / Outreach Five: Brazil, China, India, Mexico and South Africa were often described as the "G5" or Outreach Five in the context of engagement with G8 summits in the 2000s. It was not a treaty-based organisation with a permanent headquarters and should not be confused with the Sahel's former G5 Sahel framework.

EFTA: the European Free Trade Association consists of Iceland, Liechtenstein, Norway and Switzerland. The EFTA Court, which serves the EEA/EFTA judicial system, sits in Luxembourg.