Human Rights Watch on Thursday accused Kuwaiti police of using "excessive force" against opposition protesters and called on the Gulf state's rulers to respect the right to peaceful assembly.
The New York-based group said riot police had on several occasions used "what appears to be excessive force to disperse largely peaceful protesters at a series of demonstrations".
"There is no justification for attacking peaceful protesters," said Eric Goldstein, deputy Middle East director at HRW.
"The authorities should show they will not tolerate abuses by investigating all allegations of abuse by security forces and punishing those responsible for violating rights."
During huge demonstrations staged by the opposition since October 15, police frequently used tear gas and stun grenades and beat up protesters, leading to the injury of dozens and the arrest of many more, said HRW.
The Islamist, nationalist and liberal opposition, angry over an amended electoral law, has been staging protests almost every night since the December 1 poll to demand the parliament's dissolution and scrapping the amendment.
The parliament, described as totally pro-government, has however begun normal business after it was inaugurated by Emir Sheikh Sabah al-Ahmad al-Sabah on December 16.
"Kuwait's rulers need to fully respect the right to assemble peacefully," Goldstein said. "Declaring a gathering 'unauthorised' does not give police licence to beat protesters."