But what exactly is the WTO and why are promises to join not tempting enough for Iran to drop its nuclear plans?
For Iran, it is a trade-off in which its nuclear programme outweighs the profits of expanded trade, an independent international relations analyst has said.
"Iran wants to join the WTO for its economic benefits. If they join, they will be part of 90% of the world's trade giving Iran a lot of investment benefits," said
Abd Allah Baabooda, who also is a research associate at Cambridge University in the UK.
"But Iran's nuclear programme is very important and it can only drop it if the US gives it recognition and respect as a country in its own right. It doesn't want to join the WTO if a condition is to adopt US policies."
The WTO, based in Geneva, Switzerland, is the only global international organisation that deals with the rules of trade between nations.
It was established on 1 January 1995 after the Uruguay Round negotiations (1986-93).
Trade ministers signed up to the General Agreement on Tariffs and Trade (Gatt) launched in Punta Del Este, Uruguay.
"It (Iran) doesn't want to join the WTO if a condition is to adopt US policies"
Abd Allah Baabooda, international relations analyst
The round extended the range of trade negotiations, leading to major reductions in agricultural subsidies, an agreement to allow full access for textiles and clothing from developing countries and an extension of intellectual property rights.
Under the director general - Thailand's former deputy prime minister Supachai Panitchpakdi, the first WTO head to come from a developing nation - membership talks with Afghanistan and Iraq began in October 2004.
As of 13 October 2004, 148 countries were members of the organisation.
But the organisation's founding members still wield considerable clout.
"The US is easily able to block Iran from joining the WTO as it is one of the original founders of the organisation along with the EU and Japan," Baabooda said.
"These countries have strong power and any new entrants have to clear the grounds with them to join."
At the heart of the organisation are the WTO agreements, negotiated and signed by the bulk of the world’s trading nations and ratified in their parliaments.
Iran has said it will not drop its
nuclear plans to join the WTO
The WTO's goal is to help producers of goods and services, exporters and importers conduct their business.
The forum for trade negotiations handles trade disputes, monitors national trade policies, and offers technical assistance and training for developing countries.