More than 20 people were arrested in Fiji on Wednesday amid a crackdown on protesters and trade unionists.
The arrests came ahead of a planned nationwide protest on Friday over labour issues, and amid protests by hundreds of workers who had been laid-off by the Water Authority of Fiji.
Many of those arrested were workers who were locked out by the government agency, after their temporary contracts were cut short, the government said.
The total number of people detained and whether they have been charged is not known, but the government-owned broadcaster, the FBC, said over 20 "troublemakers" had been arrested.
But among those arrested were the prominent unionist Felix Anthony, who on Thursday morning was still in police custody.
Others arrested included an officer from the National Union of Workers, the General Secretary of the Fiji Teachers Association, and a representative of the Fiji Nurses Association.
A fellow trade unionist, Attar Singh, said he witnessed Mr Anthony's arrest. He said it followed a meeting with the Minister of Labour and others, including a representative of the International Labour Organisation, a UN body.
"We'd just adjourned from the meeting and were in a neighbouring conference room when the police walked in and told him that he was being arrested," he said.
Mr Singh said he understood the arrest was over an alleged breach of public order.
The government accused the unionists of planning the protests - which coincided with May Day union protests around the world - as a distraction from a major conference in Nadi.
Hundreds of delegates, including finance ministers from around Asia, are in Fiji for an Asia Development Bank meeting this week.
In a statement, the government described Mr Anthony's career as "fizzling," saying he was only focused on derailing the biggest conference ever held in Fiji.
Amnesty International called the arrests a "brazen, shocking and embarassing display of where the government's priorities lie."
The Australian Council of Trade Unions called it a "bare-faced attack on political freedom," while the New Zealand equivalent, the Council of Trade Unions, planned to picket Fiji's High Commission in Wellington on Thursday.
A NZCTU spokesperson, Sam Huggard, said the arrests were concerning.
"From nursing, education, general workers union and now just recently as well Felix Anthony the secretary of the Fiji Trade Union Congress, our sister organisation. We stand ready to support them and are deeply concerned about what's been happening in the last couple of days," he said.