BEIJING - Beijing citizens staged protests outside the Japanese Embassy in Beijing on Thursday, calling for the release of Chinese nationals who have been held by the Japanese police since they landed on the Diaoyu Islands on Wednesday.

A middle-aged man appeared in front of the Embassy of Japan, located in Beijing's Chaoyang District, at around 9:40 am, waving a piece of paper that read: "Release those who defend the Diaoyu Islands (in East China Sea) immediately and unconditionally."

Ten minutes later, another man arrived at the embassy with a piece of paper that read: "Protest against Japan's illegal detainment of Chinese warriors who defend the Diaoyu Islands."

The two protestors were persuaded by police to leave shortly after they arrived.

More than 20 people demonstrated in front of the Japanese Embassy Wednesday morning, holding China's national flags and banners asserting China's sovereignty over the Diaoyu Islands. The demonstrators shouted slogans, sang songs and read an open letter to the Japanese government.

Five Chinese activists from Hong Kong arrested by Japanese police after landing on the Diaoyu Islands in East China Sea arrived in Naha, Okinawa by Japan Coast Guard's boat on Thursday.

The five activists denied their landing as "illegal entry of Japan's territory" during inquiry by police, saying "Diaoyu Islands are Chinese territory," according to police.

Okinawa police arrested all 14 Chinese nationals on suspicion of "illegal entry" after they arrived at Diaoyu Islands by a Hong Kong fishing vessel on Wednesday to assert China's territorial claim to the islands.

On Wednesday, China's Vice Foreign Minister Fu Ying summoned Japanese Ambassador to China Uichiro Niwa and made a phone call to her Japanese counterpart Tsuyoshi Yamaguchi on the matter.

Fu reiterated China's sovereignty over the Diaoyu Islands and the affiliated islets, and demanded the Japanese side guarantee the safety of the 14 Chinese citizens and free them immediately without any conditions.

Also on Wednesday, Hong Kong's Chief Executive CY Leung said he was monitoring developments involving the detained citizens, calling on the Japanese government to ensure their safety.

Leung said the city's Immigration Department officers would go to Tokyo to provide assistance to the citizens.