China's claim of territorial sovereignty in the South China Sea could be challenged in the coming days when the White House finally gives the green light to sail a US warship near one of China's newly built artificial islands.

Citing Pentagon officials, the US newspaper Navy Times said the approval of the mission for a US Navy vessel to sail inside the 12-nautical mile territorial limit surrounding one of the man-made Chinese structures is "imminent"—an action Beijing has warned Washington not to do.

Rumours about plans to send a warship to the contested waters in the vicinity of the Spratly Islands have been circulating since May after China was reported to have started building military installations on the islands.

But the legitimacy of the islands built by China has been disputed by the US along with its regional allies, including the Philippines, who viewed it as an act of regional aggression.

Chinese Foreign Ministry spokeswoman Hua Chunying said US plans to sail a warship to the disputed islands pose serious concerns to China and cannot be taken lightly.

In May, Chunying was quoted by the Wall Street Journal as urging "relevant countries to refrain from taking risky and provocative action" off China's territorial claims.

It is unclear what the Chinese government will do when such action is taken. A report published by the Boston Globe said Beijing had issued a formal protest over a recent incident when a Chinese Navy dispatcher ''demanded eight times that a US Navy P8-A Poseidon surveillance aircraft leave the area as it flew over Fiery Cross Reef, where China has conducted extensive reclamation work.''

The US crew reportedly responded that the plane was flying through international air space.

During the UN General Assembly, US President Barack Obama was reported to have said that the "US has an interest in upholding the basic principles of freedom of navigation and the free flow of commerce, and in resolving disputes through international law, not the law of force.''

Last September, House Armed Services Committee member Randy Forbes, R-Virginia, sent a letter signed by a bipartisan group of 29 House members calling the island-building project a threat to freedom of navigation and the peaceful international order in place since the end of World War II.

"In order to deter these actions and prevent further erosion of stability in the region, the United States must make clear that it is fully committed to maintaining freedom of navigation in the South China Sea," the letter said, calling for a "highly symbolic" passage of Navy ships and aircraft past the islands to send a message to China, according to USA Today.