TOKYO: Japan and China must repair strained ties for the sake of the global economy, but rebuilding trust will take more than a high-level hand-shake, Japanese Chief Cabinet Secretary Yoshito Sengoku said Saturday. Ties between the the world's two biggest economies sank to their lowest in years after Japan's Coast Guard detained a Chinese trawler skipper whose boat collided last month with two Japanese patrol ships near disputed islands in the East China Sea. The uninhabited islands are claimed by both countries and near potentially huge oil and gas reserves. “The biggest – I won't say only – but the biggest center of growth in the world economy is Asia,” Sengoku told Reuters in an interview at the prime minister's official residence, one day before Prime Minister Naoto Kan heads for an Asia-Europe summit. “To further develop Asian economic growth, what is needed more than anything is the enrichment, strengthening and development of strategic, mutually beneficial relations between Japan and China,” he added. Japan released the boat captain last week and has been urging calm, while China has said it does not want the ongoing dispute to worsen ties further. But relations remain strained. Sengoku, the de facto No.2 in Kan's cabinet, said he could not predict whether Kan would meet Chinese Premier Wen Jiabao when the two attend the Asia-Europe summit in Brussels next week, but suggested restoring trust would be a complex process. “It is necessary not merely to shake hands at a high level but to link this to restoring trust at a practical level. I am not pessimistic, but neither am I optimistic.” Sino-Japanese ties are plagued by China's memories of Japan's past military aggression, rivalry over territory and resources, and Tokyo's fears that Beijing is beefing up its military.