A spokesman for Fiji's military regime says it will take action where it sees national security as a concern.
The military chief of staff, Colonel Aziz Mohammed, says the Fiji-born Australian academic Brij Lal was detained and questioned this week because he breached public emergency regulations.
Professor Lal says he returned to Australia after he was told to leave Fiji because of criticism he'd made of the interim regime's decision to expel Australian and New Zealand diplomats.
Colonel Mohammed would not specify how Professor Lal had breached regulations, but says the military acted of its own accord and not in response to government instructions.
He says Professor Lal was treated well.
"We had a very cordial conversation, we made the position and our concerns known to him, and basically he agreed to certain things we had to say."
Colonel Aziz Mohammed says he was not aware Professor Lal was told to leave Fiji within 24 hours.