Belarus said it suspected a group of alleged Russian mercenaries of plotting "acts of terrorism" ahead of a presidential election in August and summoned Russia's ambassador on Thursday for an explanation.

State TV on Wednesday broadcast footage of more than 30 suspected Russian private military contractors being detained near Minsk after authorities said they had received information that more than 200 fighters had entered the country to destabilize it ahead of the Aug. 9 election.

Belarus opened an investigation on Thursday into "the preparation of terrorist acts" and said that some of the captured men had already confessed to attempting to orchestrate a revolution.