The Cook Islands deputy prime minister, Sir Geoffrey Henry, has been sacked to be replaced by the opposition leader.
No reason has been given for the move.
The decision by the prime minister, Dr Robert Woonton, was made public when Sir Geoffrey was away from Rarotonga.
Florence Syme-Buchanan reports.
"In a media statement broadcast locally today, the prime minister, Dr Robert Woonton, said Sir Geoffrey will be replaced by opposition leader and leader of the Democratic Party, Dr Terepai Maoate."
Former minister Tom Marsters is being replaced by Democratic Party MP Tangata Vavia.
Both Sir Geoffrey and Mr Marsters are MPs in the Cook Islands Party which formed a coalition with Dr Woonton and his supporters early last year.
The press statement issued today said Sir Geoffrey, who is currently in the outer island of Atiu, has been advised of the change by fax.
Dr Maoate and Mr Vavia will be sworn in tomorrow morning by the Queen's Representative.
Inside sources say the change is being described by government as a cabinet reshuffle rather than the sixth coaltion the country has seen in less than four years because parliament hasn't resumed.
For Radio New Zealand International in Rarotonga, Florence Syme Buchanan.