The little ones get more and more daring but always under Gerda’s watchful eye. Picture: Svetlana Balaeva

Gerda kept her delightful cubs hidden away for three months before introducing them to the fresh air and joy of Siberian snow.

Now she takes them for a short walk in her enclosure on most days.

The little ones get more and more daring but always under Gerda’s watchful eye.

She sniffs the air for any signs of trouble.

Keepers have maintained their distance - and do not yet know the sex of the new arrivals born on 11 December 2018 - since any disturbance can upset the mother with dire consequences for the cubs.

A hidden camera revealed their birth - and now captures the cubs playing together and with their mother. Pictures: Svetlana Balaeva, Novosibirsk Zoo

They plead with visitors not to throw food or toys to the cubs nor to shout.

A hidden camera revealed their birth - and now captures the cubs playing together and with their mother.

Gerda is now a mother of four - earlier births were female cub Shilka in 2013, now at Osaka Zoo in Japan, then male Rostik in 2015, currently at Qingdao, in China.

Andrey Shilo, director of Novosibirsk Zoo, said: ‘Polar bears live in many zoos around the world, yet they are hard to raise and breed in captivity.

'There have only been a handful of cases when mother bears raised two cubs.

‘Nature had a good plan: during the first months of the cubs’ life, the mother bears eat nothing, living instead on their internal resources. Pictures: Vladimir Shadrin

‘We are hoping to see our Gerda’s twins doing well and are taking utmost care of her well-being. It is important that she feels tranquil.’

He said: ‘Our workers do not even clean the snow near her enclosure now.

‘Nature had a good plan: during the first months of the cubs’ life, the mother bears eat nothing, living instead on their internal resources.

‘We ask our visitors not to call Gerda by name, nor throw any toys or food to her.

‘She needs nothing now, and it can do harm to her. The best we can do for her is not to disturb.’