Image copyright Reuters Image caption The survey team were not allowed to land on the islands themselves

A group of Japanese officials have carried out a survey of a group of islands in the East China Sea claimed by both Japan and China.

The team was dispatched to the islands by Tokyo Governor Shintaro Ishihara.

Mr Ishihara says he plans to buy the islands, called Senkaku in Japan and Diaoyu in China, from their private owner.

Protesters from both Japan and China have landed on the disputed islands in recent weeks.

The 25-strong team sent by Mr Ishihara stayed on their boats while surveying the islands' coastlines and the waters around them.

"The governor has asked what could be done to build a small harbour. We want to check the islands with that in mind," said Seiichiro Sakamaki, the Tokyo official leading the team, according to the AFP news agency.

However, the Japanese central government did not give the group permission to land on the islands.

In July, Prime Minister Yoshihiko Noda said that his government was also negotiating to buy the islands.

Chinese official media reiterated Beijing's position that any unilateral Japanese action with regard to the islands would be "illegal and invalid".

Stunts and protests

Japan administers the islands, but China says the rocky grouping has been part of Chinese territory since ancient times.

The disputed islands sit in key shipping lanes and are thought to lie close to gas deposits.

In recent weeks the long-running dispute over the islands has flared up again.

A group of pro-China activists landed on the islands last month. Some were subsequently deported by the Japanese authorities and some sailed away from the islands.

A similar stunt by Japanese nationalist groups a few days later provoked anti-Japanese protests in several Chinese cities.

In one incident, the Japanese flag was ripped off a car carrying Japan's ambassador in Beijing.