A make-or-break summit in Bali, Indonesia aimed at paving the way for the world's biggest trade deal will succeed, despite being plagued by fierce disagreements between countries, former World Trade Organization (WTO) Director-General Pascal Lamy told CNBC.
Ambassadors from the WTO's 159 member countries have spent weeks trying to bridge differences and thrash out a last-ditch deal on new rules to ease the movement of goods globally and resolve disputes over agricultural trade.
Countries hope to agree on the proposals before the WTO's ninth ministerial conference in Bali next month, where trade ministers can give them final approval.
Despite bitter disputes between countries over aspects of the proposals, Lamy was confident that negotiations in Bali will succeed.
"It is not impossible…what has proved impossible is a consensus on the 20 issues that were bundled together in this negotiation," Lamy told CNBC in an interview in London.
(Read more: WTO warns of trade slowdown due to protectionism)
"But this year, I'm quite convinced that the Bali ministerial will work. That they will get an agreement on a major issue…which is a huge simplification of customs procedures."
If ministers agree to the trade package in Bali, this could pave the way for talks to be restarted on the global trade agreement known as the Doha Round, which aims to achieve a major reform of the international trading system, through the introduction of lower trade barriers and revised trade rules.
Negotiations over the Doha agreement, which started over a decade ago in 2001, have been stalled since 2008, after an agricultural dispute between the U.S. and India. Doha cannot be concluded until the issues that will be raised in Bali are resolved.
International trade has been on many countries' agenda over the past year. The European Union and U.S. are in the process of negotiating a massive bilateral trade deal, while a multilateral agreement known as the Trans-Pacific Partnership between 12 countries is also in the pipeline.
(Read more: US-EU trade deal: Rosy picture, but long road ahead)
Lamy, who was replaced by Roberto Azevedo in September this year, rejected claims that the WTO was irrelevant, despite numerous trade deals taking place outside its auspices.
"I don't think there has so far been a real competition or discrepancy between multilateral, global, bilateral and regional trade openings so far. What matters is that trade opens, whether you open it bilaterally, whether you open it regionally, whether you open it multilaterally," Lamy said.
"If you look in the past, multilateral, global, bilateral, regional trade openings have synergised. Now, whether it will be the case in the future I'm not sure, and that's where you need the WTO to remain the umbrella."