BANGKOK (AFP) - Thailand's government has warned of a national shortage of black clothing, which is flying off shelves as a distraught nation mourns the beloved late King Bhumibol Adulyadej.

The Commerce Ministry also said it would work with manufacturers to ensure a stable supply of mourning wear while threatening stiff punishments for price-gouging by merchants.

The ministry's director-general of internal trade Nuntawan Sakuntanaga has called on consumers to put off purchases of mourning wear until manufacturers can catch up with demand.

"The supply of black shirts may be low for a few days but garment manufacturers have insisted that there will not be a shortage, while they will quote prices as normal," she said, according to The Nation.

Since the King's death, black clothing was being sold at double the normal price in some cases, Ms Nuntawan said.

Price-gougers could face fines of up to 140,000 baht (S$5,500) and seven years in jail, she added.

Thailand has been plunged into grief by the death on Thursday (Oct 13) of King Bhumibol, who reigned for 70 years.

A range of public activities have been cancelled and television programming and nightlife has been ordered to tone down for the next month out of respect.

The directives have raised some concern that the economy would suffer, but sales of black clothing, at least, are booming.

On Friday, tens of thousands of his grieving subjects, many holding aloft portraits of the king, lined the route of a motorcade that bore his body to the royal palace in Bangkok from the hospital were he died at the age of 88.