“He's acting like the bully he is,” Bildt told the TT news agency.
“I do not know why they escalate in this way. It's no secret that they were highly annoyed by our democracy programs for a long time and now their anger over this has now exploded.”
News of the changes has been confirmed by the foreign ministry.
"We can confirm that Belarus has let us know that they're closing their embassy in Stockholm and at the same time revoked the diplomatic status for all Swedish diplomats in Belarus," foreign ministry spokesman Anna Backlund told The Local.
Bildt last week said ambassador Stefan Eriksson, who took up the post in Minsk in 2008, was expelled because of meetings he had held with the Belarus opposition.
Stockholm retaliated immediately, saying it would not welcome a new ambassador named by Minsk to replace an envoy who left the post several weeks ago, and withdrew residency permits for two Belarus diplomats who were asked to leave the Scandinavian country.
Belarus foreign ministry spokesman Andrei Savinykh denied last week that Stefan Eriksson was expelled, saying instead in more diplomatic language that "a decision was made not to renew his credentials."
Later on Wednesday morning, Bildt posted another tweet about Sweden's commitment to the country:
"We remain strongly committed to the freedom of Belarus and all its citizens. They deserve the freedoms and the rights of the rest of Europe."