Nigora Hidoyatova, the coordinator of the opposition coalition Sunshine Uzbekistan, told RFE/RL that her sister Nodira, also a member of the coalition, was arrested on 18 December on her return from Russia to the Uzbek capital Tashkent.
Hidoyatova believes the arrest is part of a government campaign to silence dissident voices.
Nigora Hidoyatova's husband, Orifjon Oidin, died of gunshot wounds on 8 December in Kazakhstan in what she has described a "political murder."
In October, the chairman of Sunshine Uzbekistan, Sanjar Umarov, was arrested on charges of embezzlement and tax evasion.
Sunshine Uzbekistan has been a vocal critic of the Uzbek government’s crackdown in the eastern city of Andijon in May, in which Uzbek officials say almost 200 people died. Other reports put the number of deaths at up to 1,000.
Speaking to RFE/RL, Hidoyatova described the government as believing that “we give you the right to make a living and for that you should be loyal to us and turn a blind eye to everything that is going on in the country.”
However, Hidoyatova struck a defiant note, saying that “we have grown up. We are the middle class and bear responsibility to our country…We feel a responsibility to say that things are going wrong in this country."