Ministers from 16 Asia-Pacific countries are expected to agree to conclude a regional free trade deal as soon as possible when they wrap up their meeting on Monday in Hanoi.

The two-day gathering of members of the Regional Comprehensive Economic Partnership came as the region is seeking to promote free trade with the outlook for the Trans-Pacific Partnership deal now uncertain after the withdrawal of the United States in January.

The RCEP involves the 10 members of the Association of Southeast Asian Nations, as well as China, India, Japan, South Korea, Australia and New Zealand. The trade framework, which accounts for more than 3.5 billion people, or half the world's population with 30 percent of global gross domestic product and trade, is viewed as a crucial regional trade pact and an alternative to the teetering TPP.

This year marks the 50th anniversary of the founding of ASEAN.

The focus is on whether the 16 nations can make concessions, with some countries seeking high-standard trade and investment rules while others are looking for swift implementation rather than the quality of the deal, Japan's trade minister Hiroshige Seko said on Sunday.

Japan and Australia have called for "high-level" rules. Japan's Prime Minister Shinzo Abe has expressed fears that China may take control over trade in the region through the RCEP, which has been promoted by Beijing.

Some analysts have voiced concern about the trade rules to be established under the RCEP, seeing the possibility that China, the biggest economy in the group, may seek to impose rules for the Asia-Pacific region favorable to itself.

RCEP negotiations formally started in 2013. Member nations have so far reached an agreement in the fields of economic technology cooperation and contribution to smaller companies.