The demand for low denomination banknotes has increased sharply ahead of Tet (lunar New Year), causing a headache for both banks and the public, but playing into the hands of black market traders.

Nguyen Thanh Lan of Long Bien District said she needed 500 VND (0.025 USD) and 1,000 VND (0.05 USD) notes to offer at Buddhist altars but after going to three banks, she was still unable to find them.

Cashiers from banks including Maritime Bank and Vietcombank said they had been unable to change money since last week because of the limited amount released by the State Bank of Vietnam .

Only regular clients and bank staff had access to the service.

Low denomination notes are used during Tet as lucky money to give to children, friends and the elderly in the belief they bring wealth, health and luck.

Le Dinh Nham, deputy director of Hanoi-based Agribank, said that for the last month, the bank had been exchanging small notes for the public, but it had got to a point where they had started to prioritise who were eligible.

Nguyen Chi Thanh, director of the State Bank of Vietnam 's Issuance and Vault Department, said besides accommodating the demand for cash at the year-end, the central bank would also issue new bills including low denomination notes.

However, the high demand for the notes would put pressure on the banking system and when Tet finished, there would be imbalanced cash circulation, Thanh said.

While banks are failing to meet the demand, black market trade is booming.

Popular spots to exchange currency in Hanoi include Hoan Kiem District's Nguyen Xi Street and Dinh Liet Street .

Smaller bills are proving more expensive, with on average a 20-30 percent mark up./.