Mannequins are dressed in black and white as retailers pay their respects after the death of Thailand's late King Bhumibol Adulyadej, at a mall in Bangkok, October 15, 2016. Reuters

Thai authorities have warned traders not to take advantage of shoppers flocking to buy black shirts to mourn King Bhumibol Adulyadej and have sent out teams of inspectors to scour markets and shopping malls for price gougers.

The 88-year-old king died on Thursday after 70 years on the throne, plunging the country into grief.

The government has declared a year of mourning and asked everyone to wear black or white, and to cancel any outdoor festivities, for the first 30 days.

“Regarding black shirts which have become more expensive, the commerce ministry has sent teams to inspect white and black clothing vendors to make sure the shirts are not being sold at prices that are too expensive,” Major General Sansern Kaewkamnerd, a spokesman for the prime minister’s office, told reporters on Saturday.

Black is the color of mourning in Thailand but white, a color that symbolizes purity, is also sometimes worn. White is also worn by ethnic Chinese people at funerals.

Most people in Bangkok have been wearing black since the king died and shoppers have been flooding to markets to get new clothes.

Traders said business was brisk and they denied pushing up prices.

“Most people are buying black shirts,” said Songkhan Tansonan, running a street stall next to a fetid canal outside Bangkok’s Bobae Market.

She said she had sold 200 black shirts by midday on Saturday and 400 the previous day.

“I buy them for 90 baht (US$2.60) from the wholesaler and sell them for 120 or 130 baht (US$3.40 to US$3.70),” she said.