A call to help make mittens for koalas injured in recent bushfires in South Australia, Victoria and New South Wales has gone viral, with mittens being sent to Australia from across the world.

The International Fund for Animal Welfare put out the call on Thursday for people to sew the cotton mittens, which are used to protect the animals' burnt paws.

Since then, thousands of mittens have been sent from as far as the United Kingdom, America and Russia.

Josey Sharrad from the International Fund for Animal Welfare said the response was astonishing.

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"What started off as a local campaign, just asking the Australian public has just absolutely gone global and viral," Ms Sharrad said.

"We're now getting offers from as far afield as Russia, Kazakhstan, China, the UK and the US.

"It's truly phenomenal."

The group has been unable to count all of the mittens, but said they had thousands and did not need any more at this time.

"It was absolutely overwhelming, we could not have planned for this and we are so touched by the kind heartedness of people all around the world," Ms Sharrad said.

"Luckily we have a big stock room and we will keep them here and send them out to people all around the country as and when they're needed."

A bushfire, that started on January 2 in Adelaide, has burnt through more then 12,500 hectares of land, destroying 27 homes and killing countless stock and wildlife.

Ms Sharrad said the exact number of koalas killed and injured in the bushfires would not be known for weeks.

Four koalas were rescued from a fire in Pottsville in New South Wales late last year, and at least two are receiving treatment in Victoria, but some have had to be euthanased as a result of their injuries, including one who received care on a roadside at Chain of Ponds in South Australia.

She said koalas were especially at risk during a bushfire due to their slow movements.

"Animals like koalas, because they are so slow moving and they live in highly flammable gum trees, they are particularly vulnerable and we're now seeing koalas come in out of that bushfire," Ms Sharrad said.

"When koalas come into care they often suffer severely burnt paws from trying to flee the fire and climb trees."

For sewers who are are still keen to help, the group has asked for pouches for other wildlife affected by the fires.

"There will be orphaned kangaroos and wallabies coming in and they need to be kept by wildlife rescuers in a very warm, pouch like environment," Ms Sharrad said.

A pattern can be found at the group's website.