Leaders of the Asia-Pacific Economic Cooperation forum have vowed to deepen cooperation on boosting trade and ensuring sustainable economic growth while indicating their concerns over "significant downside risks" to the regional economy, such as the European debt crisis.

As the leaders of the 21-member forum also pursued concrete steps Sunday toward a "seamless" regional economy during their weekend summit in Hawaii, Prime Minister Yoshihiko Noda for his part announced Japan's policy of joining multilateral talks on the Trans-Pacific Partnership free-trade framework. Nine APEC countries have already been taking part in the negotiations.

To promote "green growth" in the region — one of the key agenda items of this year's summit — the leaders struck a deal to cut tariffs on environmentally friendly goods to 5 percent or less by 2015.