Two pairs of Siberian tigers are being sent to Iran from Russia as part of a joint project to boost the species' dwindling numbers in the Middle Eastern country.
The Siberian, or Amur tigers, will arrive at the Miankaleh wildlife reserve on the coast of the Caspian Sea later this year.
The region's Caspian tigers have been almost wiped out because of excessive hunting and changes to their environment. Iranian zoologists chose the Amur tigers as a replacement because of genetic similarities.
The plan is to send the tigers to Iran during the winter to replicate as near as possible the Siberian weather conditions they are used to and reduce stress on the animals.
There are only a few hundred Amur tigers left in Russia.
In 2010, two Siberian tigers from Russia were housed at a zoo in Tehran, including a pregnant tigress, but one of them died.