The Trans-Pacific Strategic Economic Partnership Agreement was endorsed by ministers representing the four countries at the Asia-Pacific Economic Cooperation (Apec) forum's trade ministers meeting here.

Scheduled to enter into force on January 1, 2006, the pact outlines market-opening measures in areas covering goods and services, intellectual property rights and cooperation in science and technology.

The four partners said the pact would help promote free trade and liberalization and countries could join even after it goes into affect.

The combined gross domestic product of the four countries last year reached 280 billion dollars, making it a notable player in global trade.

Brunei, which had not been a member of the negotiations from the outset in 2002, was allowed to join as a founding member.