Bulgarian President Rumen Radev went into self-isolation while on an official visit to Tallinn on Tuesday after learning he may have been exposed to the coronavirus, officials said. Radev went to an investment forum after arriving in the Baltic state on Monday, before going to his hotel to quarantine. A livestream of the Three Seas Initiative conference showed Radev on a panel with the Polish and Estonian heads of state among others, none wearing masks. "It was discovered yesterday afternoon that before arriving in Estonia, President Radev had been in contact with a Covid-positive person," Estonian President Kersti Kaljulaid said on Facebook. "After the information reached Estonia, all the necessary measures were taken, and the Bulgarian delegation self-isolated at the hotel," she added on Tuesday. She said the rest of the official visit was called off as a result but did not specify how long Radev would remain in Estonia. Speaking in Bulgaria later on Tuesday, health minister Kostadin Angelov explained that the Radev -- whose role is largely ceremonial -- had been in contact with an official who had also quarantined. Bulgaria has seen a significant uptick in coronavirus infections in recent weeks, leaving many provincial hospitals struggling. bur-amj/mas/jxb