Liberal senator Jim Molan has refused to accept the apology of a Greens MP who questioned his military record in Iraq, insisting his threat of defamation is still on the table.

Melbourne Greens MP Adam Bandt suggested in a TV interview on Wednesday the senator may have committed war crimes during the battle for Fallujah.

'I want him to reconsider it': Molan says he was deeply disappointed by Brandt's apology. Credit:AAP

Senator Molan, a retired major-general who served as the chief of operations of the US-led coalition forces in Iraq, quickly threatened to pursue the Greens MP through the courts for defamation.

He invited Mr Bandt to "end the problem" and avoid legal action by making a public apology.