Mobile phone subscribers in Belarus received an anonymous SMS alleging that plotters were preparing bloodshed after Sunday's election and warning them to keep away, an AFP report said.
"On the evening of the 19th on Oktyabrskaya Square, provocateurs are preparing bloodshed. Look after your life and health," the message read.
The report said the message followed a warning by President Alexander Lukashenko that he would not tolerate unrest after the presidential vote, which opponents said had been rigged.
Security forces had warned that opponents were planning to seize power by force and had said that demonstrations could be classed as terrorism, the report said.