Kuwait has said rioting and violence would be met with a firm response after it made several arrests at a protest over the conviction of an opposition politician for insulting the country's ruler.
Witnesses said police fired teargas on Wednesday to disperse thousands demonstrating against the conviction of former member of parliament Musallam al-Barrak, who was sentenced to five years in jail for the comments last year.
Despite Kuwait saying it was a fair hearing, Monday's trial has rekindled tension after a period of relative calm following a parliamentary election in December, with supporters staging nightly protests in the OPEC member state.
"Any form of riot, violence, instigating of riots and violence or lawlessness would meet (a) resolute and firm response," the Interior Ministry said on state news agency KUNA.
Some protesters engaged in "acts of rioting and violence", on Wednesday, the ministry said, adding that some people had been arrested, without giving numbers.
It said people had fired shots into the air "to provoke security personnel", and protesters had aimed fireworks at police, some of whom had to be taken to hospital. It accused them of setting fire to public property and halting traffic.
Barrak has yet to be taken into custody since the court's verdict and special forces entered his guest house and a neighbouring home in a district west of Kuwait City to try to find him on Wednesday, before the protests, without success.
He later gave a speech, alongside other opposition figures, to protesters who gathered outside the house before taking to the streets. It was not immediately clear why special forces did not try to arrest him then.
Kuwait has avoided mass Arab Spring-style unrest but citizens held large street protests last year after the emir, Sheikh Sabah al-Ahmad al-Sabah, changed the electoral law, a move the opposition said was aimed at preventing them from winning a parliamentary majority.
The government said the move brought Kuwait in line with voting systems elsewhere.
Although the US ally allows more political freedom than other Gulf states, the emir has the last say in state affairs. He is deemed "immune and inviolable" in the constitution and shielded from public criticism by the penal code.
Barrak, who like other opposition politicians boycotted the election, was one of the most outspoken critics of the new voting system. Dozens of opposition activists have been charged with remarks deemed offensive to the emir, mainly made on social media.