The Fiji Trades Union Congress general secretary, Felix Anthony, is still being questioned by police.
Fiji Live online reports the Assistant Police Commissioner, Henry Brown, saying the ongoing investigation is similar to the charges laid against FTUC president Daniel Urai.
Mr Anthony was taken in for questioning last Friday and Mr Brown says investigations are continuing.
Daniel Urai is currently in custody and his bail ruling will be delivered in the Suva Magistrates Court today.
He appeared in court on Monday charged with urging political violence and inciting antagonism against the Fiji Government.
Meanwhile, the interim Attorney General, Aiyaz Sayed-Khaiyum, says in the case of Felix Anthony and Daniel Urai, the Government does not comment on ongoing trials.
He also added that statements or speculation made by outside parties - such as those made by Former Australian Prime Minister Kevin Rudd - are patently false and based on misinformation.
Kevin Rudd had said the arrest of the pair is another example of what appears to be a concerted campaign by the Fiji authorities to target and intimidate trade unionists and other political opponents.