Indonesian police have arrested two men on Sumatra island with six tiger skulls and other parts from the critically endangered species, an official said Monday.
The two were held Saturday in Pekanbaru city of Riau province as they picked up a package containing the skulls, five pieces of skin and bones, the provincial conservation agency head Trisunu Danis Woro said.
"It seems that the tigers have been killed a few days ago," he told AFP adding that the package was delivered from Aceh province on the northern tip of the island.
"The men are not the main actor. Someone has ordered them to pick up the package," he said.
There was no mention on the package of the sender's identity and police were still hunting the culprits behind the poaching network, he said.
Conservationists estimate there are fewer than 400 Sumatran tigers left in the wild because of habitat loss and poaching.
In June Indonesian police arrested a man who allegedly poisoned and skinned an endangered Sumatran tiger in a state-owned zoo.
Representatives from 13 "tiger-range countries" met last week in Bali and drew up a declaration in a bid to save the big cats from extinction.
Explore further: Research shows impact of BMR on brain size in fish