Singapore, Sept. 27 -- Up to 50 sites across Singapore are retailing unbranded diesel at half the price posted at regular pumps operated by the oil giants.

This is three times the number of so-called "white pumps" when The Sunday Times last reported on the trend in 2014.

These sites are mostly in industrial areas such as Sungei Kadut, Woodlands and Tuas.

Checks by The Sunday Times revealed that at least one is in a mixed district of Sin Ming, which has half a dozen nozzles, and even a car-wash. The site sits right next door to a National Environment Agency regional office.

Diesel is around $1.50 per litre at regular stations, but is 70 to 80 cents a litre at these white pumps, which are sited on plots far cheaper than those occupied...