A senior US State Department official has reiterated that the Senkaku Islands in the East China Sea are clearly covered by the Japan-US security treaty.

US Assistant Secretary of State Kurt Campbell was speaking at a hearing of the Senate foreign relations subcommittee on East Asian and Pacific Affairs on Thursday.

Tension is growing between Japan and China over a territorial dispute involving the Senkaku islands.

Campbell said the United States is concerned by recent demonstrations in China and by the potential damage the dispute could cause to the partnership between Japan and China.

He said the United States is not taking a position on the ultimate sovereignty of the islands. But Campbell said the US views Japan as maintaining administrative control of the islands.

He also spoke about China's creation of a new administrative area in the disputed islands in the South China Sea in July and strengthening military presence in the area.

He said he did not expect these moves, and expressed concern over the military measures in particular.

Meanwhile, a US defense source says Defense Secretary Leon Panetta told the Chinese Vice President that the disputed islands in the East China Sea are covered by the US-Japan security treaty.