Two of the activists, Jalal and Jawad Fairooz, are former MPs from al-Wefaq, the mainstream Shia opposition movement, which is at the centre of a confrontation with the Sunni-led government. The brothers are visiting the UK and may now be forced to make high-profile asylum applications that will be awkward for the relationship between the British and Bahraini governments.
Others include the London-based dissidents Saeed al-Shehabi and Ali Mushaima, the son of the jailed opposition leader Hassan Mushaima. In April, Ali Mushaima climbed onto the roof of Bahrain’s embassy in London to publicise demands for democratic change.
Last week the government in Manama banned all demonstrations, though it backed down in the face of British criticism and said the ban was only temporary.
It was not clear whether the men will be expelled from Bahrain.
Bahrain’s ruling Al Khalifa dynasty imposed martial law and sought help from its Gulf neighbours to put down Shia-led protests against alleged discrimination that began in February last year. But unrest continues with protesters and police clashing almost daily. On Tuesday the government said it had arrested four suspects in bombings that killed two people in Manama and accused the Iranian-backed Lebanese group Hezbollah of being behind the attacks.
Bahrain is often described as lying on the sectarian fault line of the Arab world and on the frontline of a tense confrontation between Iran and its Gulf Arab neighbours. It is also home to the US fifth fleet. Bahrain regularly accuses Tehran of encouraging unrest, though there is no evidence of any direct involvement.
Ali Alaswad, a former Wefaq MP, said: “This is a totally inhumane and unwarranted measure that exposes the real mindset of the government. This is one of a series of recent measures that constitute a renewed and repressive crackdown against the opposition and is a hundred miles away from the dialogue and reform promised by the government. It is the clearest evidence yet that even Al Wefaq, the moderate opposition, is being targeted by the crackdown. We have not seen such a sustained attack on the opposition since the period of military rule in 2011.”
In a similar move last December, the United Arab Emirates revoked the citizenship of seven Islamist activists, claiming they posed a threat to national security. Some of the men had demanded greater powers for the Federal National Council, an elected body that advises the government. In a week that has seen David Cameron visiting the UAE and Saudi Arabia, the British government has been criticised for prioritising defence exports and trade over human rights in its relations with the Gulf autocracies.
Bahrain’s monarchy has made a series of concessions, including giving more powers to the elected parliament, but opposition groups say the reforms do little to loosen the ruling family’s hold on power. More than 50 people have been killed in Bahrain’s unrest since February 2011.