The nationalists raised Japanese flags on Uotsurijima just days after Tokyo deported pro-Beijing protesters who had landed on the island. China had warned against acts "harming" its territorial sovereignty.

More than a hundred people gathered near the complex housing the Japanese consulate in China's southern city of Guangzhou, chanting "Japan get out of the Diaoyu Islands," the official Xinhua news agency said.

In nearby Shenzhen, which borders Hong Kong, protesters gathered at an outdoor plaza, waving Chinese flags and shouting slogans, Xinhua said, but did not give the number of participants.

Zhang Pei, one participant, said protesters were marching towards the train station on the border with Hong Kong.

"The demonstration is strung out for seven to eight kilometres (four to five miles). Many police are escorting us along the street," he told AFP by telephone.

He could not give an estimate of the number of protesters, but said participants were swelling as the march continued.

Xinhua said protests also took place in four other cities, including eastern Hangzhou and Qingdao, as well as the northeastern cities of Shenyang and Harbin.

Beijing on Saturday rebuked Japan over the planned island visit.

"China has made solemn representations to Japan, demanding that it immediately cease actions harming China's territorial sovereignty," the foreign ministry said in a statement.

Anti-Japan protests have broken out in several cities in the past week, including the capital Beijing, commercial hub of Shanghai and Qingdao and Binzhou in the eastern province of Shandong, state media and witnesses said.

The island is part of a chain claimed by China. China calls the archipelago Diaoyu, but it is controlled by Japan, which calls it Senkaku.

On Saturday, hundreds gathered in the northern city of Xian to protest over the detention of 14 pro-China activists and journalists who had sailed from Hong Kong to land on the islands, Xinhua said in a separate report.

Japan on Friday deported the 14 people, who were arrested after arriving in the area on Wednesday.

Around a dozen members of the right wing group Gambare Nippon (Hang In There Japan) swam ashore, an AFP journalist witnessed, from a 20-boat flotilla carrying activists and lawmakers.

The landing comes just days after Tokyo deported pro-Beijing protesters who had landed on the island, part of a chain administered by Japan but claimed by China, which had warned against acts "harming" its territorial sovereignty.

There was no immediate official reaction from Beijing, but anti-Japanese protests were reported in a number of cities.

Local Tokyo politician Eiji Kosaka, one of the men who made it to the island, said the group had planted Japanese flags on a hillside and on the shore.

"This is undoubtedly Japanese territory," he told an AFP reporter aboard the flotilla on his return. "On the mountain we found (the ruins of) Japanese-style houses that had places for drying fish.

"It is very sad that the Japanese government is doing nothing with these islands," he said, adding the nationalists' expedition had been "a great success".

By mid-morning all the approximately 150 people who had sailed to the islands, including eight parliamentarians, were back on the boats and were heading back to far southwestern Ishigaki. They had spent around five hours there.

Japanese coastguard ships had urged the activists not to land, with officers boarding some of the vessels to question people. No arrests were made.

China fiercely claims the archipelago, which it calls Diaoyu, but it is controlled by Japan, which calls it Senkaku.

The state-run Xinhua news agency said Sunday protests had erupted in six cities, with more than a hundred people gathering near the complex housing the Japanese consulate in southern Guangzhou, chanting "Japan get out of the Diaoyu Islands".

In nearby Shenzhen, which borders Hong Kong, protesters gathered waving Chinese flags and shouting slogans, Xinhua said.

One participant said protesters were marching towards the train station on the border with Hong Kong in a demonstration strung out over up to eight kilometres (five miles).

Xinhua said at least four other cities were also affected.

Before the voyage, Kenichi Kojima, a local politician from Kanagawa, near Tokyo, told AFP the trip was about who owned the archipelago, whose seabed is believed to harbour rich mineral resources.

"I want to show the international community that these islands are ours. It is Japan's future at stake," he said.

Organisers, who had been refused permission by Tokyo to go ashore, said ahead of their departure that they would be holding a ceremony aboard boats to remember some of those who died in World War II.

In Tokyo, Tsuyoshi Yamaguchi, the senior vice foreign minister, said established practice was for only government officials to land there.

But, he added: "In principle, it is alright for Japanese people to visit Japanese territory."

Beijing on Saturday rebuked Japan over the island visit.

"China has made solemn representations to Japan, demanding that it immediately cease actions harming China's territorial sovereignty," the foreign ministry said in a statement.

The dispute over the islands is one of the major stumbling blocks -- along with issues related to Japan's military occupation of parts of China during World War II -- to smooth relations between Asia's two giant economies.

Tensions spiked as Japan deported 14 pro-China activists who sailed to the islands from Hong Kong.