King Bhumibol, the ninth king of Thailand's 234-year-old Chakri Dynasty, died on Thursday in Bangkok. The king was venerated as a pillar of stability and his death has plunged the country of 67 million into mourning.

In Dinso road, a stone's throw from the Grand Palace, where King Bhumibol's remains will be kept for about one year until a royal cremation is held, shops selling gold-framed portraits of the king were packed and business was brisk.

"Business has increased about 70 to 80 percent," said Charlie Wangthamrongwit (62) who owns a shop in Dinso road, known by some as 'portrait street'.

"We just can't meet demand," he said, adding that standing portraits of King Bhumibol were proving the most popular.

"Everything king-related is in demand now," he added, as shoppers queued in the searing heat outside his shop.

Parts of Bangkok were decked out in black and white funeral bunting on Monday and portraits of the king framed with black cloth dotted the Thai capital.

"There are no orders to remove portraits of the king," government spokesman Weerachon Sukondhapatipak told Reuters.

"We are instructing people on ways to rearrange the portraits correctly. For example, the phrase 'Long live the king' is now obsolete so we are correcting that," he said.

King Bhumibol reigned for 70 years and most Thais have known no other monarch in their lifetimes. His portrait is displayed in schools, banks and on the front of government buildings.

Recently, portraits of the king's son and successor, Crown Prince Vajiralongkorn, have also increased.

But vendors said they have not yet received orders for the prince's portrait.

"Nobody has ordered the prince's portrait yet. Right now we are in a period of mourning," said Charlie.

The military-led government has said the prince has asked for a delay in proclaiming him king so that he can mourn with the people.

It has declared a year of mourning and asked that any outdoor festivities be cancelled for the first 30 days. Most shops, bars and other entertainment venues, including cinemas, remain open.

Many Thais are wearing black to mourn the king.

Deputy Prime Minister Somkid Jatusripitak said he had met with the Thai Garment Manufacturers' Association and asked them to accelerate production of black clothing.

"If we don't have enough, we can produce more right away," said Chatchai Tuangrattanapan, director of the Thai Retailers' Association.

Volunteers with gas burners heating black dye offered free dyeing services near the palace on Monday.

In Dinso road, school teacher Vatchara Reantaiseng, 31, loaded his car with black and white cloth.

"It's difficult to find this cloth at the moment but we know that in this neighbourhood, we can."