It’s a case of when, not if a deadly bird flu pandemic arrives in Australia, the country’s top medical expert is warning, as almost $100 million is allocated to deal with an outbreak.

The federal government will spend $95 million preparing for the H5N1 strain of bird flu, which has caused respiratory illness, reduced egg production and sudden death among wild birds and some mammal species in other countries.

The H5N1 strain of bird flu is different to the strain in Australia earlier this year that’s led to egg shortages in supermarkets.

Australia is the only continent without the H5N1 strain but chief medical officer Paul Kelly says it’s coming.

“It’s really when, not if, this arrives, and we’ve seen in other parts of the world, whilst there has been rather mild human disease so far, this virus is changing very quickly,” he told reporters in Canberra on Monday.

Agriculture Minister Julie Collins said migratory birds would bring the flu strain to Australia, making it difficult to stop.

“What we are doing in terms of preparedness and the reason we’re doing this, is to make sure that we maintain food security and food safety,” she said.

Environment Minister Tanya Plibersek said about 500 bird species and 80 mammal species had been affected by the bird flu strain, which could impact threatened species in Australia.

“Spring is the most likely time for it to hit because of those migratory bird species that will come in from countries where this strain is prevalent,” she said.