Human Rights Watch (HRW) has called on Kuwait to stop targeting opponents through revoking their citizenship and to reinstate the nationalities of 33 people affected by the practice.
"Kuwaiti authorities should immediately stop stripping nationals of their citizenship because they exercise free speech or other legitimate human rights," New York-based HRW said in a statement.
They should "reinstate the citizenship of people whose citizenship has been withdrawn on those grounds," it added.
The oil-rich country, where citizens elect their parliament and which is traditionally seen as one of the more tolerant Gulf monarchies, was damaging its reputation, HRW said.
In the past few months, Kuwait has revoked the citizenship of 33 people and most of their family members.
HRW said that at least three of the cases appeared to be politically motivated.
In July, Kuwait withdrew the citizenship of the family of Ahmad Jabr al-Shemmari and shut down his satellite television station and newspaper, as the country was hit with a new wave of anti-government protests.
In August, Kuwait revoked the citizenship of a former Islamist opposition politician and his brothers and sisters, in addition to 10 activists, including leading cleric Nabil al-Awadhi.
Also stripped of his nationality was Saad al-Ajmi, spokesman of the Popular Action Movement, a nationalist opposition group.
A government statement last month said some of those who lost their citizenship had been naturalised because of fake documents.
Others had dual citizenship, which is outlawed in Kuwait, and some had their nationality revoked for security reasons, the statement said.
"The Kuwaiti authorities seem to think they can use the cover of the nationality law to target their critics and deter dissent," said Nadim Houry, deputy Middle East director at HRW.
"But Kuwait's real message of official intimidation has rung out loud and clear," he said.
"While Kuwait continues to strip people of citizenship for no good reason, its reputation as a tolerant country will continue to nosedive."