China said Thursday that the establishment of the city of Sansha in the South China Sea is an affair within the country's sovereignty.

"We are willing to reiterate that the establishment of the city of Sansha is a readjustment by the Chinese government to existing administrative bodies, which is an issue within China's sovereignty," the spokesperson's office of the Chinese Foreign Ministry said in a written reply to Xinhua.

"The Chinese side will continue to be committed to seeking appropriate solutions through bilateral negotiations and consultations with the parties directly involved in the concerned disputes, based on respect for historical facts and international laws," according to the statement.

On Tuesday, a U.S. State Department spokesperson expressed concern over the current situation in the South China Sea but did not respond directly to a question about the establishment of the city.