The whereabouts of detained rights activist Rocio San Miguel and five members of her family were unknown, Venezuelan advocacy groups and lawyers said on Monday.
San Miguel, 57, was detained on Friday afternoon at Simon Bolivar International Airport, near the Venezuelan capital Caracas.
Tarek Saab, Venezuela's attorney general, said on Sunday that she was being held because of her alleged involvement "in the conspiracy plot and attempted assassination" of President Nicolas Maduro.
Authorities in Venezuela arrested dozens of individuals, including soldiers and civilians, for their alleged role in a plot to assassinate Maduro.
Saab had also confirmed at the time that 11 other people — including activists, journalists and soldiers — had been issued arrest warrants for the alleged involvement in conspiracy plans that also allegedly targeted Defense Minister Vladimir Padrino.
What do we know about San Miguel's disappearance?
Five of San Miguel's relatives are now missing, including her daughter, said Juan Gonzalez, one of her lawyers.
The activist's lawyers have submitted a court query asking why San Miguel was arrested and inquiring about her whereabouts, Gonzalez added.
San Miguel's daughter Miranda and ex-husband Victor Diaz Paruta were among those missing, their lawyers said. A family spokeswoman told the Associated Press news agency that authorities had not acknowledged their detention.
The father and daughter were last seen at the Simon Bolivar International Airport on Saturday, where they had returned to pick up San Miguel's luggage following her arrest.
Two brothers of the activist were also missing, the AP reported.
Several rights organizations have condemned San Miguel's arrest. The US government also expressed concern.
rmt/msh (AP, Reuters)