DUBAI, United Arab Emirates (AP) — A Bahraini human rights group says a female rights activist has been detained for the second time in two months amid a crackdown on dissent in the Gulf island kingdom.

The London-based Bahrain Institute for Rights and Democracy said on Tuesday that Ebtisam al-Sayegh was taken into custody by masked, armed police shortly before midnight the previous day.

The group says authorities presented no arrest warrant and did not say where the 48-year-old was being taken.

Amnesty International has expressed concern that al-Sayegh alleged she was tortured and sexually assaulted during a previous detention in May.

Bahraini authorities did not respond to a request for comment on Tuesday. The country, which hosts the U.S. Navy's 5th Fleet, has previously said it is opposed to any kind of mistreatment.