Bahrain’s Shia-led opposition says it will boycott parliamentary elections planned for November.
Five opposition groups, including the Al-Wefaq movement, said in a statement that the vote was an attempt to establish “absolute rule in Bahrain”.
It comes a day after a government minister said that all sides should participate in the democratic process.
The polls will be the first since anti-government protests rocked the Sunni-ruled kingdom in 2011.
Dozens died when the government moved to quash the demonstrations.
The protesters had been demanding more rights and an end to discrimination against the majority Shia community by the Sunni royal family.
Since then talks intended to resolve tensions have collapsed, and protests have continued. Thousands of people have been arrested.
The opposition groups announced on Saturday they would be refusing to take part in the government’s “sham” elections, claiming they would be unfair.
On Friday, Information Minister Sameera Ebrahim Bin Rajab said participation in the elections was a “free national duty” and condemned the opposition groups’ plans for a boycott.
“They tend to raise the banner of boycott in an attempt to open the door for foreign interference in our domestic affairs,” she said, quoted by Bahrain News Agency (BNA).
Last week Nabeel Rajab, a leading Bahraini human rights activist, was arrested and charged over Twitter remarks deemed “denigrating” to government institutions.
Sunni Muslims are a minority in the country but through the al-Khalifa dynasty have ruled over the Shia Muslim majority for more than 200 years.
The small island country is a key US ally in the Gulf and hosts the US Navy’s 5th Fleet.
Bahrain is also closely allied with Saudi Arabia, which in 2011 sent troops into the country to help the government quell the uprising.