A survey group organized by Tokyo metropolitan government departed from Ishigaki port, Okinawa, at Saturday night and headed to the Diaoyu Islands in the East China Sea, local media reported.

The group is expected to arrive at the islands at 5:00 am Sunday morning and return to Ishigaki at night, according to media reports.

Tokyo metropolitan government said it plans to study the natural environment of the Diaoyu Islands because it's a necessary step for buying the islands.

The investigation group comprises a total of 25 people, including officials from Tokyo and Ishigaki government, estate valuers and a university professor.

Tokyo government earlier sent a landing application, but was rejected by the central government Monday for security reasons.

Tokyo is also preparing to hold another survey on the Diaoyu Islands in October in which the governor of Tokyo Shintaro Ishihara will take part.

Ishihara has announced in April that the Tokyo government plans to purchase three of the five uninhabited islands.