HANOI (AFP) ― China’s vice president was ending a visit to Vietnam on Thursday, part of an effort to consolidate ties that deteriorated following recent tensions over the disputed South China Sea.

Both sides said Xi Jinping’s three-day visit to Hanoi “further consolidates and promotes relations between the two parties, countries and people,” according to the Vietnamese government’s website late Wednesday.

The communist neighbors have had a long-standing dispute relating to sovereignty over the Paracel and Spratly island groups, which are in oil-rich waters straddling vital commercial shipping lanes in the South China Sea.

On this matter, “the Vietnamese side agreed to be ready, with China, to solve disputes through peaceful negotiation, respecting and paying attention to each other’s legitimate benefits,” the report said.

The official Chinese news agency Xinhua added that the two neighbors “agreed to earnestly implement the consensus and the agreement in order to maintain stability in the South China Sea”.

Relations sank to their lowest point in years in May and June when Vietnam said Chinese vessels twice interfered with its oil survey ships inside the country’s exclusive economic zone.

In July a Chinese warship confronted an Indian naval vessel in waters off Vietnam and demanded it explain its presence.

Vietnam Communist Party General Secretary Nguyen Phu Trong visited China in October, where both sides agreed to keep in frequent touch on the maritime issues.

But last month Vietnam’s premier reaffirmed before the National Assembly his country’s sovereignty over the two archipelagoes. For the first time, he condemned China for using violence to take the Paracels from Vietnam in 1974, a year before the end of the Vietnam war.

China says it has sovereignty over essentially all of the South China Sea, where its professed ownership of the Spratly archipelago overlaps with claims by Vietnam, the Philippines, Taiwan, Brunei and Malaysia.

The two countries fought a brief border war in 1979 before normalizing relations in 1991.

China has been Vietnam’s leading trade partner since 2004, and two-way trade has risen from $32 million in 1992 to $30 billion in 2010.

On Wednesday, China committed a $300 million preferential credit for Vietnam’s infrastructure improvement.