Washington: Expressing concerns over the use of force by China against a Vietnamese exploration ship in South China Sea, United States has said incidents like these raise significant maritime security threats.

"We have been troubled by some of these reports about the South China Sea, and believe they only serve to raise tensions and don't help, obviously, with the peace and security of the region," Mark Toner, State Department spokesman said.

"As the Secretary (of State) said last year in Hanoi, we've got a number of national interests that we share with the international community in the South China Sea.

"Obviously these incidents in the last couple of days raise significant maritime security issues, including the international community's freedom of navigation, unimpeded economic development and commerce, and respect for international law," Toner said.

"Our position remains clear."We believe that customary international law provides unambiguous guidance on the appropriate use of the maritime domain and rights of access to it," he said.

"We support a collaborative diplomatic process by all claimants to resolve various territorial disputes without coercion, and call on all claimants to conform all of their claims, both land and maritime, to international law," Toner said.

Meanwhile Senator Jim Webb, chair of the Senate Foreign Relations East Asian and Pacific Affairs Subcommittee, expressed "grave concerns" over the repeated use of force by China to assert maritime territorial claims in the South China Sea.

"China's pattern of intimidation is a grave concern. The US has a clear strategic interest in facilitating a multilateral, peaceful approach towards resolving these disputes and ensuring open access for commerce and adherence to international law," Webb said.

On Monday, Webb will introduce a Senate resolution condemning the use of force by China in the South China Sea and calling for a peaceful, multilateral resolution to maritime territorial disputes in Southeast Asia.