Prime Minister Junichiro Koizumi and ambassadors from member states of the Association of Southeast Asian Nations agreed Wednesday to reinforce ties at an upcoming Japan-ASEAN summit.

"The biggest message would be to maintain and reinforce cooperation, nurtured for a long time, in the future as well," Koizumi said in a meeting with ASEAN ambassadors to Japan, a Japanese official said.

ASEAN ambassadors welcomed Japan's recent decision to join the Treaty of Amity and Cooperation in Southeast Asia, a nonaggression treaty signed by all ASEAN members. They said they are encouraged that Japan is placing importance on the ASEAN in political and security fields as well as the economy.

Japan agreed last week to join the TAC, which was crafted in 1976 to maintain a peaceful relationship among Asian countries.