China's relations with the United States remain stable, Chinese President Xi Jinping said on Sunday, as he sought to defuse tension over a territorial dispute in the South China Sea that has pitted Washington against Beijing.

"I look forward to continuing to develop this relationship with President Obama and to bring China-U.S. relations to a new height along a track of a new model of major country relationship," Xi told U.S. Secretary of State John Kerry at the end of Kerry's two-day trip to China.

Kerry's trip has been dominated by deepening security concerns about Beijing's maritime ambitions in the South China Sea. China's rapid reclamation effort around seven reefs in the Spratly archipelago of the South China Sea has alarmed claimants such as the Philippines and Vietnam.

On Saturday, Kerry urged China to take action to reduce tension in the South China Sea. His call was rebuffed by China's Foreign Minister Wang Yi, who said Beijing's determination to protect its interests in the area is "as hard as a rock".

Kerry's trip is intended to prepare for the annual U.S.-China Strategic and Economic Dialogue next month in Washington and Xi's expected visit to Washington in September, a trip that Xi said he looked forward to.

Xi has repeatedly told Obama of his desire for a "new model of major country relationship," in which China would be viewed as an equal global player.

But the model also outlines a respect for "each other's sovereign and territorial integrity as well as political system and development path".

"In my view the China-U.S. relationship has remained stable," Xi told Kerry at Beijing's Great Hall of the People at a session open to reporters.

China claims about 90 percent of the 3.5 million sq km (1.35 million sq mile) sea. The Philippines, Taiwan, Malaysia, Brunei and Vietnam also claim large parts of it.

Recent satellite images have shown that since about March 2014, China has conducted reclamation work at seven sites in the Spratlys and is constructing a military-sized air strip on Fiery Cross Reef and possibly a second on another reef.

The Philippines, a U.S. treaty ally, has called for urgent action.

Kerry said the United States had stated its concerns about the pace and scope of China's land reclamation in the South China Sea.

On Saturday, China's top diplomat, Yang Jiechi, urged Kerry to "properly control our differences and sensitive issues" as well as "view our strategic intentions objectively and rationally", according to a report by state-run China News Service.

"I hope the United States can do more for peace and stability in the region," Yang, who holds the title of State Councillor, was quoted as telling Kerry, referring to the South China Sea.

China has expressed its concern about a possible U.S. plan to send military aircraft and ships to assert freedom of navigation in the South China Sea.

China rejects U.S. involvement in the dispute and has blamed the United States for stoking tension by encouraging countries to engage in "dangerous behavior".