As Thais snap up black clothes to mourn the loss of King Bhumibol Adulyadej, a government spokesman has urged the public not to condemn those who are dressed in other colours.

Some may be too poor or cannot find them because of short supply, Lieutenant-General Sansern Kaewkamnerd told reporters yesterday. "If you can't find a black or white shirt, you can put a black or white ribbon on your shirt, on your arm or chest. Make it appropriate in your way. I would also like to ask the society not to judge these people."

The comments came after some Thais were scolded or criticised on social media for not donning black as a sign of respect for the monarch, who died last Thursday at the age of 88 following a long illness.

King Bhumibol reigned for 70 years and was seen as a unifying father figure for the often politically turbulent nation.

The Thai government has declared a one-year mourning period and asked the people to refrain from entertainment for one year. Guidelines for media outlets require TV presenters and announcers to be dressed in white or black, The Nation reported.

Over the weekend, Thais flocked to shops to stock up on black clothing, while window displays in shopping malls were changed to showcase attire in black, white or grey.

But some Thais have criticised their countrymen for not dressing in the appropriate colours. Mobs in southern Thailand have also descended on the homes of people accused of insulting the king.

Under Thai law, anyone who insults or defames the king, queen, heir apparent or regent can be jailed for up to 15 years on each count.

Last Saturday night, a crowd confronted the family of an alleged lese majeste offender in Phang Nga province. In a Facebook Live video posted by "JJ Khomta", one person could be heard saying: "This is the land of father, if you don't like him, go away!" Soldiers had to be called in to control the situation.

Meanwhile, the government has stepped up scrutiny of offensive comments about the royal family.

Yesterday, telco providers asked customers to report inappropriate comments about the monarchy, following a request from the state broadcasting and telco regulator, said Reuters news agency. Last Friday, the regulator told Internet service providers to monitor and block inappropriate content and to inform platforms such as Facebook, Twitter and YouTube to do the same.