Senior diplomats from Japan and China are arranging to hold talks Thursday to discuss suspected gas field explorations by Beijing in a contested area of the East China Sea, diplomatic sources said Saturday.

Japan will lodge a protest against the development work and repeated intrusions by Chinese ships into Japanese waters around the Japan-controlled, China-claimed Senkaku Islands, the sources said.

At the first virtual meeting at the director-general level since last November, Japan will be represented by Takehiro Funakoshi, head of the Asian and Oceanian Affairs Bureau at the Foreign Ministry, while China is set to field Hong Liang, who is in charge of boundary and ocean affairs.

Earlier this month, the Japanese government confirmed new construction work by China that is suspected to be for gas field exploration in the contested area. The Japan Maritime Self-Defense Force found Chinese ships transporting what would be the "foundation" of a new structure on the west side of a Tokyo-proposed median line separating the countries' exclusive economic zones in the sea.

File photo taken in September 2012 shows the Senkaku Islands in the East China Sea. (Kyodo)

On May 20, Japan said it confirmed another area of ongoing construction by China in nearby waters. Including the latest one, Tokyo has been aware of 18 structures developed by Beijing on the Chinese side of the median line in the sea, according to Japan's Foreign Ministry.

Japan and China agreed to jointly develop gas in the area in 2008, but negotiations were suspended in 2010 when tensions increased following a Chinese trawlers collision with a Japan Coast Guard vessel.

Japan regards the median line as the demarcation line between the two neighbors under domestic law, but China says its EEZ extends much further.

The sources said Tokyo will raise the issue of a joint overflight by Chinese and Russian strategic bombers in May over waters near Japan, adding it will also take up discussions on the creation of an emergency hotline between the Japan Self-Defense Forces and the Chinese People's Liberation Army to avoid unintentional contingencies.

Japan will again lodge a protest with China during the talks regarding a Chinese research vessel conducting a suspected survey in Japan's EEZ, according to the sources.