Discount clothing retailer Uniqlo said warmer weather and "aggressive" sales activities had driven an 18.3% surge in like-for-like sales at its Japanese stores in May.

Total retail sales were up 25.5% over the same period, while overall revenues - including direct sales - increased 25.7%.

"May sales exceeded the previous year's level thanks to our aggressive sales activities and the persistent warm weather during the month," said Uniqlo.

The company conducted polo shirt, UT (print t-shirt), bra-top and sports campaigns during the month.