On a visit to Vietnam earlier this month, US Secretary of State John Kerry said that the proposed Trans-Pacific Partnership (TPP) could well be signed by the end of the year.

Speaking in Hanoi, he said that the 12 countries negotiating the free-trade pact (including both the USA and Vietnam, as well as Japan) had made “good progress” during the recent round of talks on the Hawaiian island of Maui.

Vietnam does not allow independent trade unions, and some members of its Communist government worry that a trade deal may result in more freedom for employees.

However, at a joint press briefing with Vietnamese Foreign Minister Pham Binh Minh, Mr Kerry said he was sure that the matter was not “a sticking point,” adding “we will do everything possible to work through any differences”.

If the deal goes ahead, the TPP will cover nearly 40% of the global economy. The pact, which excludes China, has been eight years in the making and is seen as part of US President Barack Obama’s so-called ‘re-balance’ towards Asia.

The other countries included in the negotiations include Australia, Brunei, Canada, Chile, Malaysia, Mexico, New Zealand, Peru and Singapore. Mr Obama has reportedly said that the deal must be signed this year, in order for it not become to an issue in the 2016 US presidential election.