Bahrain has revoked entry visas issued to Human Rights Watch to attend an international parliamentary conference, the rights group said on Friday, days after raising concerns about the Gulf state's rights record.
The event would have marked the first time that HRW representatives had been able to enter the Gulf state since 2012.
Bahrain, a US ally, will from Saturday host the 146th assembly of the Inter-Parliamentary Union (IPU), an international organisation with the motto "For democracy. For everyone".
HRW, which has permanent observer status with the IPU and was granted the visas earlier this year, had on Monday called for conference attendees to raise concerns about what it called "the serious repression of human rights in Bahrain".
Bahrain's government communications office and the IPU did not immediately respond to requests for comment.
Rights groups, including HRW, have criticised Bahrain for holding international events, such as last week's annual Formula One race, as a way of distracting from repression of political opposition.
The Sunni Muslim-ruled state has, since a 2011 anti-government uprising led largely by its Shi'ite Muslim community, jailed thousands of people, including opposition leaders, sometimes in mass trials. It has also dissolved leading opposition groups.
Bahrain's government says it has made key reforms in recent years on human rights, criminal justice and prisoner treatment.
"(Bahrain's) unilateral reversal of Human Rights Watch's access to the IPU conference is a blatant example of its escalating repression," said Tirana Hassan, HRW's acting executive director.
HRW members have not been granted access to Bahrain since 2012, a spokesperson said.