Vietnam’s annual inflation rate accelerated to 25.2 per cent in May, the fastest since 1992, highlighting the challenge facing the country’s Communist authorities as they seek to cool the overheated economy.

The surge in prices, up from 21 per cent in April, was driven by a 67.8 per cent year-on-year increase in the price of grain – the staple food, which accounts for 42.8 per cent of the basket of goods and services Hanoi uses to calculate its inflation rates.