Kuwaiti police have used teargas and smoke bombs to disperse thousands of protesters marching on a prison where an opposition leader is being held over remarks deemed critical of the emir, the interior ministry and activists say.
Wednesday's unrest comes amid rising tension caused by changes to the election law, which the opposition had condemned as an attempt to give pro-government candidates an advantage in parliamentary elections on December 1. The opposition are boycotting the poll.
Defence lawyers said on Wednesday prosecutors had charged Musallam al-Barrak on three counts related to a speech in which he made critical remarks about the 83-year-old emir, and ordered him held for 10 days pending further questioning.
Thousands later marched towards the prison demanding Barrak's release. Some carried a poster showing Barrak behind bars. "Set free the conscience of the nation, Musallam al-Barrak," a caption read.
Police ordered the crowd to disperse and then used teargas and smoke bombs.
The Interior Ministry said security forces dispersed rioters who had blocked streets and assaulted police with stones and bottles, according to a statement carried by the state news agency KUNA.
The ministry blamed "violent agitators and instigators" for the trouble said it had made some arrests and warned further protests would be dealt with harshly.
Barrak, an outspoken former member of parliament, was picked up from his home on Monday, two weeks after an opposition rally at which he made rare critical remarks about the emir, Sheikh Sabah al-Ahmad al-Sabah. At the rally, Barrak had appealed to Sheikh Sabah to avoid "autocratic rule".
Prosecutors have charged him with encroaching on the pillars of the emirate, insulting the emir and infringing his authority, said a defence lawyer who asked not to be named.
Kuwait's constitution says the emir is "immune and inviolable". Insulting him carries a penalty of up to five years in jail.
Three other former legislators were earlier detained on similar charges, questioned and freed on bail pending trial, scheduled to start on November 13.
When the emir ordered changes to electoral rules, the opposition announced a boycott of the election and organised one of the biggest protests in Kuwait's recent history, bringing tens of thousands onto the streets.
The government has since banned gatherings of more than 20 people and pushed ahead with preparations for the election. The Information Minister told a news conference that candidate registration began on Wednesday under new rules that allow each voter to pick one candidate instead of four, as previously.
The minister said that under the changes, which also include setting up an election commission, each candidate will get a slot to discuss his or her platform on state television.