Authorities are now selecting people only from Pyongyang who have children living in the country to reduce the number of defections.
Reports suggest the more than 200 Uyghurs are being interrogated ahead of deportation to China.
Many use the seashore as the focus of their commemoration, in a reference to the burial of Liu's ashes at sea last weekend.
Internet service providers in Xi’an are being ordered to keep personal files on any social media account holder with more than 30,000 followers.
