Xi Jinping has appealed to Vietnam to join China in upholding multilateral trade, as he begins a high-stakes diplomatic tour of the region’s major export-reliant economies in a bid to position his country as a stable partner in contrast to the United States.

President Xi Jinping will meet Vietnam's leaders in Hanoi on Monday as he begins a three-nation trip to Southeast Asia, aiming to cement ties with some of China's closest neighbours amid mounting trade tensions with the United States.

Chinese leader Xi Jinping warned Monday that protectionism "leads nowhere" and that a trade war would have "no winners", state media said, as he was due to kick off a tour of Southeast Asia with a visit to Vietnam.