Kuwaiti riot police fired tear gas and stun grenades at hundreds of opposition supporters who demonstrated on Tuesday for the third time this month to press for dissolving parliament.
Many people suffered from breathing problems after inhaling a new type of tear gas used for the first time by police, witnesses told AFP.
Chanting anti-government slogans, protesters called for dissolving the new pro-government parliament, elected last month after the opposition boycotted the polls in protest against the controversial electoral law.
The protest, staged in tribal-dominated Sabahiya, about 30 km (19 miles) south of Kuwait City, was led by a number of former opposition lawmakers, including Mussallam al-Barrak.
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Protesters also called for an elected popular government in this Gulf state where the emir, crown prince, prime minister and key ministers are from the Al-Sabah family in power for more than 250 years.
Barrak strongly condemned on Twitter what he called police violence, saying this will not stop opposition protests, which will continue until the realisation of "a constitutional monarchy and elected government."
Opposition figures have threatened to take police atrocities against activists to international human rights organisations and to parliaments in Western countries, including the US Congress.
The opposition has protesting a government amendment to the electoral law which it says allows the government to impact the outcome of an election.
The Gulf state has been rocked by a series of political disputes between MPs and the government since mid-2006 .