The witnesses in the trade union's tax evasion case are detained after refusing from their testimonies in court, citing pressure.
BelaPAN editor-in-chief Iryna Lewshyna did not show up at work on 9 August, her mobile phone switched off.
The stickers appeared on the equipment after a search in BELSAT office in the spring of 2017, BELSAT cameramen say.
Some editions have been getting warnings from BelTA for a few months.
Journalists Ihar Hmara, Maria Saroka, Alena Maslouskaya and Uladzislau Kuletski were released after an interrogation on August 8.