The request emerged during talks between visiting Japanese Foreign Minister Fumio Kishida and Vietnam's Prime Minister Nguyen Xuan Phuc and Foreign Minister Pham Binh Minh, a Japanese spokesman said.
"Vietnam wants new vessels," Masato Otaka told reporters, adding that timing, methods of delivery, costs and quantity of vessels had not yet been decided.
Vietnam has been modernising its military, and recently bought six advanced Kilo-class submarines from Russia.
Russia and India are the main source of advanced weapons, training and intelligence cooperation. Hanoi is also buildingties with the United States and its Japanese, Australian and Filipino allies, as well as Europe and Israel.
"Vietnam feels it needs to strengthen its coastguard generally, and that's why we've responded," Otaka told reporters, adding that the vessel delivery "was not directly linked to the South China Sea".
- Reuters