HANOI, June 27 - China's top diplomat arrived in Vietnam on Monday for a scheduled meeting to strengthen historically close relations, at a time when ties are strained by squabbles over the East Vietnam Sea.

The trip by State Councillor Yang Jiechi, who outranks the foreign minister, comes amid a Chinese public relations blitz to try to discredit a looming verdict by an international tribunal that could aggravate tensions if it undermines Beijing's vast claims to waters extending far into Southeast Asia.

Yang was due to co-chair a "steering committee" that aims to strengthen ties and ward-off disputes. He will make courtesy calls on the Vietnamese leadership later on Monday.

"We're glad to realize that the two nations' relationship over the time continues its positive development, despite some existing problems that need to be solved," Vietnam's Foreign Minister and deputy premier Pham Binh Minh said after greeting Yang.

China has said at least 47 countries have offered support for its refusal to recognize a high-profile case brought by the Philippines in 2013 to the Permanent Court of Arbitration in the Hague. A senior U.S. official last week voiced skepticism about that claim.

Chinese diplomats have written editorials in regional newspapers denouncing the Philippine case, which seeks clarification of parts of United Nations maritime law and is seen as a bold challenge, with scope for repercussions.

Experts say it is unlikely Yang would seek a sympathetic ear from Vietnam, which has trust issues with China and has recently grown closer to the Philippines.

Though Vietnam is not part of the Hague case, it stands to benefit from a positive ruling for Manila and has echoed its opposition to China's fortification of artificial islands, the conduct of its coastguard and perceived intrusions into Vietnam's exclusive economic zone.

Ha Hoang Hop, a Vietnamese academic who has advised the government, said there was "no hidden agenda" behind Yang's visit and there were no compromises to be made over the East Vietnam Sea.

The Hague ruling is expected in the coming months and there are concerns in the United States about how China could react should the verdict not work in its favor.

China and the United States have accused each other of trying to militarize a shipping route vital to the stability of the global economy.