Singapore has seized more than 28 tons of pangolin scales belonging to around 38,000 of the endangered mammals over the past week, a global record that spurred calls for more protection for pangolins, which are used in traditional medicine.

The scales, which were found in shipping containers, have been linked to four species of pangolins native to Africa.

Government officials found a record 14.2 tons of the scales hidden among packets of frozen beef on April 3. Five days later, they found 14 more tons in 474 bags in another container. National parks and customs officials said in a statement Wednesday that the cargo was declared as cassia seeds, which are used to make tea. Both shipments were heading to Vietnam from Nigeria.

“The sheer size of these two latest seizures is unprecedented and will undoubtedly prove a major setback to the traffickers concerned,” said Richard Thomas of monitoring network Traffic.

He warned that the seizures themselves won’t put the traffickers out of business. The number of scales shows that the shipment was part of a large business, Thomas said.

The pangolin is said to be the most widely trafficked mammal in the world, and its scales are in high demand in Asia for use in traditional Chinese medicine. The scales are made of keratin, the same material in human fingernails. Their meat is also considered a delicacy in China and other Asian countries.

Wildlife groups are concerned that the busts point to a jump in poaching of pangolins.

“The World Health Organization recently endorsed traditional medicine and the industry appears keen to grow this market, outside of China, Vietnam and beyond,” said Neil D’Cruze, the global wildlife adviser at the World Animal Protection. “This is an alarming move for some wildlife species such as pangolins, as it poses a real conservation and animal welfare threat.”

Pangolins can bring in a large income for hunters, he said. Poachers can make up to the equivalent of a full year’s salary from catching just one pangolin.

Paul Thomson, an official at the Pangolin Specialist Group, said it looks like the pangolin poaching has increased but figures were difficult to verify.

“The illegal trade in pangolin parts has been going on for decades. However, pangolins have typically been overlooked in terms of concerted conservation attention and action,” Thomson said. “This is changing thanks to growing awareness of pangolins. And this awareness has partly been driven by the high volumes of trafficking seen today.”