An official Chinese newspaper says improved relations between the US and Vietnam must not lead to greater pressure on China or threats to its interests.

The China Daily said in an editorial Tuesday that any attempt by the US to use Vietnam as a foil to China could further complicate regional tensions.

The comments point to Beijing's underlying concerns about closer ties between its chief regional rival and its southern neighbor, with which it is in dispute over ownership of islands in the South China Sea.

China on Monday formally welcomed Washington's decision to fully lift a five-decade arms embargo on Vietnam during a visit by President Barack Obama, saying it is happy to see Vietnam develop "normal and friendly cooperative relationships with all other countries, including the United States."