Quarantine officials have euthanised two tiny primates smuggled into Brisbane on an international flight this morning.

The slow lorises were found running free in the cabin of a plane that had left Dubai.

A number of passengers are being questioned.

Australian Quarantine Inspection Service (AQIS) spokesman Colin Hunter says although the South-East Asian primates are endangered, they had to be put down.

"Our standard operating procedures require us to contain any potential biosecurity or human health risk," he said.

"The animals arrived without documentation so therefore under standard operating procedures; unfortunately we're required to euthanise."