Bahraini authorities arrested dozens of Shia clerics in sweeping raids overnight on Saturday amid an intensifying crackdown triggered by the US-Israel war on Iran .
The country's interior ministry said it had detained 41 people who it said were linked to Iran's Revolutionary Guards.
It claimed to have uncovered an organisation linked to the paramilitary group and arrested a number of its alleged members, according to a statement carried by the state news agency.
The war has emerged as a flashpoint in the Sunni-ruled country, whose large Shia population have staged small sporadic protests expressing sympathy for Iran.
Bahrain, which hosts a major US naval base, was among the hardest-hit Gulf states by Iran's retaliatory drone and missile strikes.
Among those arrested on Saturday were some of the country's most prominent Shia religious figures, including sheikhs Mohammed Sanqour and Ali Al-Sadadi.
"This scale of arrests has not happened in our lifetimes," human rights activist Sayed Ahmed Alwadaei told The New Arab , calling recent government actions "unprecedented".
Unlike during the Arab Spring protests, authorities are targeting people on sectarian lines and carrying out a "persecution of the Shia," said Alwadaei, head of advocacy at London-based NGO Bahrain Institute for Rights and Democracy.
Al-Wefaq, a Shia political party outlawed following the 2011 protests, described the arrests as part of a "systematic crackdown tied to political expression and public positions regarding the war against Iran".
The unrest triggered by the war has been met with an escalating campaign of repression against the Shia majority involving hundreds of arrests, heavy jail sentences , and dozens of people stripped of their citizenship .
Most of the arrests have been in relation to peaceful protests against the war and critical posts on social media.
A 32-year-old man, Sayed Mohamed Almosawi, died in custody after being arrested, with rights monitors reporting signs of torture on his body.
Meanwhile, three lawmakers were expelled from the parliament on Thursday after opposing moves by King Hamad bin Isa Al Khalifa to arbitrarily strip Bahrainis of their citizenship. The king had earlier suggested the MPs could also be deported for voting against the decree.
Last month, 69 people had their citizenships revoked for allegedly sympathising with Iran.
Around 350 people have been detained by authorities since the start of the war, said Bahraini human rights researcher Sayed Almuhafdha, who described the current period of repression as the worst since 2011.
Those arrested in Saturday's raids are likely to lose their citizenships and some could face the death penalty, he told The New Arab .