Thailand is set to become the 12th country to join Pacific Rim trade talks.
A government spokesman confirmed its entry into the TransPacific Partnership will be formally announced when President Barack Obama visits the country next week.
Thailand has free trade agreements with all countries in the talks except the United States, Canada and Mexico.
New Zealand has had preferential access to the Thai market since signing a free trade deal with ASEAN countries and Australia in 2010.
The 15th round of negotiations for the TransPacific Partnership is to be held in Auckland early next month.