The Chinese Foreign Ministry is contacting the Japanese side to lodge representations over the detention of five Chinese nationals on the Diaoyu Islands, according to an announcement from the ministry on Wednesday.

Japan detained the five people from Hong Kong, who landed on the island on Wednesday afternoon to assert China's sovereignty claim over the islands, alleging they had made an "illegal entry."

Two other Chinese nationals who also landed on the island returned to the fishing vessel, according to Japanese police.

The five detained may be transferred to the Immigration Bureau of Japan later and sent back to Hong Kong, a spokesman from the Japan Coast Guard told Xinhua.

The fishing vessel carrying the Chinese nationals departed from Hong Kong on Sunday, according to previous media reports.