Thousands of demonstrators waving Japanese flags and shouting anti-China slogans marched Saturday against Chinese Premier Hu Jintao's visit for an economic summit that comes as a territorial dispute strains ties between the Asian giants.

Organizers said Saturday's march in Yokohama, which was held under heavy security near the site of the Asia-Pacific Economic Cooperation forum summit, drew about 4,000 demonstrators. Police had no official estimate of the crowd size.

Relations between Japan and China have plunged recently because of tensions over a ship collision near islands in the East China Sea that are controlled by Japan but also claimed by China. Called the Diaoyu or Diaoyutai in Chinese and Senkaku in Japanese, the islands are surrounded by rich fishing grounds and are regularly occupied by nationalists from both sides.

The island dispute has also generated large anti-Japan protests across China and attacks on Japanese-owned businesses there.

"Our reason for being here was to demonstrate that we want to protect our territory from China. Those islands are our territory," said Norihiko Ueda, the protest's organizer. The group that launched Saturday's protest has held several other large rallies over the territorial dispute. It is headed by a former air force general known for his hawkish views.

Protesters also waved the flags of Tibet, east Turkmenistan and south Mongolia and shouted "defeat Chinese imperialism." China is sensitive to ethnic national movements rejecting Beijing's control of each of those regions.

Though the group that organized the protest is right-of-center, emotions have been high among a broad swath of Japanese who feel that their country — which invaded and colonized parts of China during World War II — is being bullied by a China newly emboldened by its economic rise and swelling international clout.

Some shoppers applauded as the march passed by Yokohama's biggest train station.

Diplomatic ties remain shaky.

After the Sept. 7 collision, Beijing cut off ministerial-level contacts with Japan, and it was unclear until the last minute whether Hu would meet with Japanese Prime Minister Naoto Kan here. A meeting was set up for Saturday.

The two met informally at another summit in Hanoi last month, but Hu refused to put Kan on his official agenda.

Some in the protest Saturday said they thought Japan and China need to do more to maintain friendly relations.

"I think China is a threat to Japan. But I also think the Japanese and Chinese have to discuss this," said Sayo Kuroda, a 19-year-old college student who joined the protest with her family.