China on Monday announced that it would sign a treaty establishing a “nuclear weapons free” zone in south-east Asia, a largely symbolic move that signals its increasing willingness to forge closer ties with regional nations.

Wen Jiabao, China’s premier, made the announcement in Nanning, southern China, where he is meeting the leaders of the 10-strong Association of Southeast Asian Nations in a summit to mark 15 years of relations with its member nations.