The lawyer for the Taimi O Tonga newspaper says the Tongan Government should immediately rescind a new ban on the paper, to demonstrate respect and compliance with the rule of law.
New Zealand QC Dr Rodney Harrison, in a letter to Tonga's Solicitor General, says it is transparently obvious the new ban is unlawful and unconstitutional.
The Tongan Privy Council imposed the new ban, through an Order in Council, on Friday, soon after a court ruling that three previous bans on the paper were illegal.
The Government's chief secretary says a key motivation for the new ban was because the Supreme Court had chosen for the first time to review a Privy Council Order.
Dr Harrison says in his letter that, at the very least, the earlier ruling makes the new ban unlawful and unconstitutional.
He also says the section of the Constitution giving the power to pass such an Order, can only be used as an emergency and not when there are statutes, such as the Prohibited Publications Act, already in place.
Dr Harrison says the Government's actions against his clients will not be accepted or tolerated, and claims for substantial damages will be pursued.