Rare Amur leopards born at British zoo

One of two five-week-old Amur leopard cubs looks out into its enclosure at Twycross Zoo.

(CNN)A British zoo has announced the birth of two Amur leopards -- believed to be the world's rarest big cat.

Twycross Zoo, in Leicestershire, central England, has released the first images of the as yet unnamed five-week-old cubs.
The animals have begun venturing outside their den, and visitors can now catch a glimpse of them on a live-stream shown on a big screen outside the leopards' enclosure.
    Amur leopard Kristen watches as one of her cubs explores their enclosure.
    Native to the forests and mountains of Russia's far east, Amur leopards are a critically endangered species. They are on the brink of extinction in the wild, under threat from habitat loss and poachers hunting them for their fur.
    There are thought to be less than 70 leopards left in the wild, with 200 more living in zoos across the world.
    The new arrivals are the second pair of cubs born to mum Kristen and dad Davidoff. The first pair were born in 2014.
    Twycross staff hope the two cubs and their older siblings will help to ensure the long-term survival of the species.
    One of the as yet unnamed cubs rolls around in its enclosure.
    The first pair of cubs, Arina and Alexei, are already moving towards adulthood -- in the wild, Amur leopards usually leave their mother before they turn two.
    Arina moved to Highland Wildlife Park in Kincraig, Scotland, earlier this year and Alexei will soon be taken to Estonia's Tallinn Zoo.
    Dr Charlotte Macdonald, Director of Life Sciences at the zoo, said the birth of the new cubs was "fantastic news" for the entire species.
    In April, Twycross celebrated the first birth of a rare Diana monkey in the UK in five years and the first at the zoo for 29 years.