Dubai Three activists were detained from Fahoud oil fields on Thursday for visiting the site to show solidarity with the striking workers from contracting companies, working for two oil companies in the country.
Former Oman volleyball player Habiba Al Hinai, Sohar activist Esmail Al Muqbali and Yaqoub Al Kharusi were held by security forces, according to a rights group in Oman.
The three had gone to support the striking Omanis, who are working for Petroleum Development Oman (PDO) and Oxy Oman contractors.
The workers are on strike for more than a week demanding better wages, risk allowance and provision for pension.
The strike has been termed illegal and workers have been asked to report back by around nine contracting companies. The workers have been warned they could risk losing jobs if they continue the strike.
Some of the Shura members and prominent citizens have tried to intervene.
According to a Facebook post by an activist, the last contact with Esmail Al Muqbali was on Thursday morning.
Esmail Al Muqbali, Habiba Al Hinai and Yaqoub Al Kharusi are among some activists who formed an independent human rights body. Oman already has a Human Rights Commission.