The Cook Islands high commissioner to New Zealand, Dr Robert Woonton, has been sacked for plotting to topple his own Government.

Cooks Minister of Foreign Affairs, Wilkie Rasmussen, dismissed Dr Woonton from the island country's most prestigious overseas posting after discovering his involvement with some island MPs in a failed bid to oust the Government of Prime Minister Jim Marurai.

Dr Woonton, a former Prime Minister of the Cooks, has been given three weeks to vacate the country's high commission office in Wellington.

Mr Marurai said an attempt to form an alternative government by members of both the Opposition and Government had failed, Radio New Zealand International reported.

Both the Government and Opposition claimed a majority in the 24-seat Parliament after two Government MPs, Piho Rua and Upoko Simpson, last week aligned themselves with the opposition Cook Islands Party.

But Mr Marurai said his Cook Islands First Party, in coalition with the Democratic Party and two new cabinet members lured from the CIP had a two-seat majority.

The Prime Minister said Dr Woonton and a Wellington-based developer, Tim Tepaki were involved in the manoeuvring over the parliamentary majority.

The Cook Islands Herald reported on Friday there had been a series of meetings by a group of politicians to bring down the Government.

The Herald reported that Dr Woonton had played a prominent role in those meetings and that he was to be relieved of his position in Wellington.

Mr Tepaki is a property developer who wants significant changes to land laws in the islands and to revive the Italian hotel project at Vaimaanga.

- Special correspondent, NZPA