Political opposition groups in Bahrain have walked out of talks with the government, aimed to bring an end to the two and a half years of unrest, after the arrest of one of the most senior Shia political figures in the country.

Khalil al-Marzooq, political assistant to the Al-Wefaq party’s secretary-general, was summoned to a police station on 17 September and is currently being detained for 30 days. The government says he is being investigated for links to the Coalition of 14 February Revolution Youths, a loose network of activists calling for the removal of the ruling Sunni Al-Khalifa monarchy.

Al-Marzooq and Al-Wefaq are signatories of a declaration of non-violent opposition. Opposition groups say the charges are a result of a speech Al-Marzooq gave on 7 September that was critical of the government.

Human rights groups have criticised the politician’s arrest and demanded his release. “Al-Marzooq is a prisoner of conscience, imprisoned only for his vehement criticism of the government,” says Hassiba Hadj Sahraoui, Middle East and North Africa deputy director at Amnesty International. “He must be immediately and unconditionally released. Over recent months, the Bahraini government has increased its threats and attacks against political associations that are critical of the government, in particular al-Wefaq.”

Tensions between the government and Shia opposition groups are running high, particularly after King Hamad bin Isa al-Khalifa issued a decree in July that significantly curtailed political activities on the island. The decree banned demonstrations and public gatherings indefinitely and was followed in September by another that forced political associations to notify the government three days before any meeting with a foreign diplomat. The latest decree also said meetings between political societies and diplomats must now take place in the presence of an official from the Foreign Affairs Ministry.