A meeting of Asean senior economic officials that ended on Tuesday concluded that the deal was likely to be signed at the Asean economic ministers' meeting in May if all nations are ready, said Winichai Chaemchaeng, the department's deputy director-general.

Japan has proposed that the pact be signed in February.

Mr Winichai said Thailand's signature requires cabinet approval according to Article 190 of the Constitution, and any ratification must be endorsed by Parliament.

Mr Winichai said the agreement would cover trading in goods, mainly agricultural, fishery and chemical products. Activities related to trade, services and investment have mostly been determined by bilateral free trade agreements between each nation and Japan.

Asean-Japan free trade agreement negotiations started almost four years ago in pursuit of a ''comprehensive economic partnership'' within 10 rounds of talks.

The agreement is expected to boost the volume of regional trade to more than $163 billion a year.

Japan was Asean's second-largest trading partner in 2006 after the United States, with two-way trade totalling US$162 billion. Asean exports to Japan were worth $81.28 billion, with imports were valued at $80.49 billion.

Mr Winichai said once the agreement is signed and implemented, 90% of import duties for Japan from Asean would be brought down to zero.

Thailand is also expected to benefit from the agreement, as it would complement the existing economic cooperation between Bangkok and Tokyo under the Japan-Thailand Economic Partnership Agreement (JTEPA).

Under the Asean-Japan FTA, Asean and Japan would eliminate tariffs on 71 kinds of products worth $53 million.