Vietnam is protesting China's fishing ban in parts of the South China Sea that Hanoi claims as its own.
Foreign Ministry spokesman Luong Thanh Nghi says in a statement posted on the ministry's website late Tuesday that Vietnam considers China's decision "invalid."
China's seasonal ban begins Wednesday and is meant to curb overfishing in the South China Sea. But parts of the sea also are claimed by Vietnam, the Philippines, Malaysia, Brunei and Taiwan. The sea has valuable fishing grounds and shipping lanes, and is believed to be rich in oil and gas.
Vietnam and China have recently engaged in spats in disputed waters, and a marine standoff between the Philippines and China over an uninhabited shoal has gone on for more than a month.