Top Obama aide in sea talks with China

US National Security Adviser Susan Rice will urge Beijing next week to avoid escalation in the South China Sea when she makes the highest-level US visit to China since an international court rejected its sweeping claims to the strategic waterway.

Even as Washington has sought to keep a lid on the situation, Rice - in an interview with Reuters - vowed that the US military would continue to "sail and fly and operate" in the South China Sea, despite a Chinese warning that such patrols could end "in disaster".

With less than six months remaining of President Barack Obama's tenure, Rice's broader mission in her July 24-27 trip is aimed at keeping overall ties between the world's two largest economies, which she called "the most consequential relationship we have," on track at a time of heightened tensions.

"I'll be there to advance our co-operation," she said.

But the trip, due to be formally announced later on Friday, follows a July 12 ruling by the Permanent Court of Arbitration in The Hague that China has no historical title over the waters of the South China Sea.

Beijing has angrily rejected the verdict and pledged to pursue claims that conflict with those of several smaller neighbours.

"I've been in communication with our Chinese counterparts over the last couple of weeks," Rice said.

"We understand each other's perspectives clearly. We'll urge restraint on all sides."

Rice is expected to meet Chinese President Xi Jinping during her visit and her agenda will include North Korea, economic issues and human rights. She will also lay the groundwork for Obama's talks with Xi at a G20 summit in China in September, US officials said.