The judicial authorities in French Polynesia have rejected a bid by the secretary general of the confederation of independent unions, Cyril Legayic, to be released from jail.
Mr Legayic was arrested last month and transferred to Tahiti's Nuutania prison as part of an investigation into alleged corruption.
He is in detention with a New Caledonian businessman, Bill Ravel, who is alleged to have paid Mr Legayic 160,000 US dollars in cash over four years to contain strikes at his companies in Papeete.
Another suspect, Gaston Tetuanui, is also in jail amid claims that as a go-between, he took some of the money.
Mr Ravel's New Caledonia-based associate, Kim Than Trong, has been questioned in Tahiti after he was arrested in Noumea and flown to Papeete amid a broadened investigation.
So far, two politicians, Oscar Temaru and Jean-Christophe Bouissou, have publicly declared their innocence in the affair