Tehran will not "give in to the political and smear campaigns" over the jailing of British-Australian academic Kylie Moore-Gilbert, Iran's foreign ministry said.

Ms Moore-Gilbert, a Cambridge-educated academic who was most recently a lecturer in Islamic Studies at Melbourne University, has been in Tehran's notorious Evin prison for more than a year, having reportedly been given a 10-year sentence.

It was reported Ms Moore-Gilbert and another jailed, French-Iranian, academic, Dr Fariba Adelkhah, had begun a hunger strike on Christmas Eve.

In an open letter published by supporters and confirmed by the Centre for International Research at Sciences-Po where Dr Adelkhah works, the two women said: "We will strike on behalf of all academics and researchers across Iran and the Middle East, who like us have been unjustly imprisoned on trumped up charges and simply doing their job as researchers.

"We have been subjected to psychological torture and numerous violations of our basic human rights."

When asked by reporters if he was concerned for Ms Moore-Gilbert's welfare, Australian Prime Minister Scott Morrison said he was, adding: "As I am for any Australian who finds themselves in these types of situations."