The Fiji Labour Party says the Electoral Commission should question Rear Admiral Frank Bainimarama for flouting the law around political parties.
The party's leader Mahendra Chaudhry says the prime minister's announcement one of his ministers will be joining his political party contravenes the Political Parties Decree.
Mr Chaudhry says the party would like to see the regime leader register his political party as required by the law before he campaigns further.
"He hasn't got a political party as yet therefore he cannot engage in active campaigning and engage in political activities. It is a contravention of the Political Parties Decree and I think the authorities here should take action in the matter particularly the Electoral Commission should question the announcement and question the conduct of Bainimarama."
Mr Chaudhry says the Labour Party will be raising the issue with the Electoral Commission.
The Political Parties Decree imposes a fine of up to US$27,000 and a jail term of up to five years if an association of persons or an organisation operates or holds itself out to be a political party unless it has been registered as one.