Kuwait on Thursday released on bail opposition leader Mussallam al-Barrak after a night of violent protests against his detention that left dozens hurt, his lawyer and an AFP photographer said.
Opposition groups which held an emergency meeting in the wake of the night-long clashes strongly condemned the government's "barbaric suppression" of peaceful demonstrations, saying Kuwait was becoming a police state.
"A judge ordered the release of Barrak on bail of 10,000 dinars ($35,600) pending trial," lawyer Abdulrahman al-Barrak told AFP after the defence team submitted a petition against the 10-day detention.
Around 200 supporters greeted Barrak when he stepped out of the central jail, 25 kilometres (16 miles) southwest of Kuwait City.
Barrak was arrested on Monday and charged with undermining the status of Kuwait's emir at a public rally on October 15, for which he could face a jail sentence of up to five years, his lawyer said.
Amnesty International called for the charges to be dropped, saying Barrak's arrest was "outrageous and ... yet another manifestation of the increasing restrictions on freedom of expression and assembly in Kuwait."
The opposition insisted it will continue holding peaceful protests and called on the government to "halt its unprecedented oppressive and police practices," in a statement signed by 11 political and youth groups.
It called on the government to release all detainees and to scrap the disputed amendment of the electoral law that triggered the current standoff which has turned violent at times.
The disturbances in the OPEC member state saw the Kuwait Stock Exchange index dive about 2.0 percent to 5,645.31 points on Thursday.
The interior ministry, meanwhile, reiterated that it will not allow any new unauthorised demonstrations, including a procession planned by the opposition on Sunday.
Thousands of protesters on Wednesday marched on the central jail to demand freedom for Barrak, a former lawmaker, before police confronted them with tear gas and stun grenades.
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Clashes continued into the early hours of Thursday and spread to several areas of the Gulf state.
Five policemen were wounded during the overnight clashes when two vehicles hit them and sped away, according to an earlier statement by the interior ministry.
The ministry said police arrested several protesters without giving a number but witnesses told AFP that at least 23 people were detained.
Activists said that dozens of people, especially children, were rushed to hospital after inhaling gas when riot police made extensive use of stun grenades and tear gas canisters in their attempt to disperse the protesters.
The activists said police chased demonstrators in the Sabah Al-Nasser area, a predominantly tribal district near the central jail, into homes and beat them up.
Police also clashed with demonstrators in residential areas near the oil hub of Al-Ahmadi, around 40 kilometres south of Kuwait City and also in northern Kuwait.
The violent protests were the second major confrontation between police and the opposition in the past 10 days. On October 21, more than 100 people and 11 policemen were hurt during a massive protest.
Tensions have been simmering since the emir Sheikh Sabah al-Ahmad al-Sabah on October 19 said he had ordered the government to amend the controversial electoral law, which was changed two days later.
The opposition claims the change is aimed at electing a rubber stamp parliament.
Kuwait is scheduled to hold snap polls on December 1 which almost all opposition groups have announced they will boycott. It will be the second election this year and the fifth since mid-2006.
The Gulf state has been rocked by a series of ongoing political disputes since 2006 during which the cabinet was forced to resign nine times and parliament was dissolved on six occasions.