China will sign an investment agreement with ASEAN on Saturday, marking the completion of talks on the world's largest free-trade area (FTA) in terms of population.

The pact will be inked at the 12th China-ASEAN Summit (10+1) in Pattaya, Thailand, to be attended by Premier Wen Jiabao, the Foreign Ministry announced on Wednesday. Wen left Beijing and arrived there for the meetings on Friday.

"It's like a good medicine with time-release properties taking full effect after a decade," Wang Yuzhu, an ASEAN studies expert with the Chinese Academy of Social Sciences (CASS), told the website of Shanghai-based Xinmin Evening News.