Officials said doctors at the Police General Hospital had decreed that Thaksin could receive no more than 10 visitors on Monday from 8am to 3pm.
Among the people visiting the former premier were his three children and three lawyers.
At about 2pm, Paetongtarn was spotted walking out of the building and heading to her car. She declined to answer any questions posed by reporters.
Meanwhile, Thaksin’s lawyer Vinyat Chatmontri told reporters that the former premier was under close medical watch and that his condition remains worrying.
He also appeared reluctant to answer questions, saying Paetongtarn will announce all details on Tuesday.
Many opponents have claimed that Thaksin is receiving special treatment despite facing many charges.
After spending some 15 years in self-imposed exile, the former premier returned to his motherland last Tuesday. He was taken to the Bangkok Remand Prison before being transported to the Police General Hospital for treatment of hypertension and other symptoms.