A parallel trade agenda between China and the United States is essential for the expansion of global trade liberalization, according to the former World Bank president Robert Zoellick.

Speaking to China Daily in Shanghai, Zoellick said it is important for the world's largest two economies to push ahead with service sector reforms via the World Trade Organization, even if the US expands its involvement in the Trans-Pacific Partnership Agreement, a free trade pact effective within an exclusive bloc of nations.

The creation of the TPP has been controversial because negotiations surrounding its expansion have largely been taking place in secret.