The source said no embassy staff had been harmed during the incident.
Hundreds of protesters stormed the Swedish embassy in Baghdad in the early hours of Thursday morning and set it on fire, a source familiar with the matter and a Reuters witness said.
The source said no embassy staff had been harmed and declined to elaborate further. Swedish embassy officials in Baghdad did not immediately respond to requests for comment.
The protest was called by supporters of Shi'ite cleric Muqtada Sadr ahead of an expected burning of the Muslim holy book, the Koran, in Sweden - which in the past has led to widespread protests and condemnation in Muslim-majority nations.
A series of videos posted by One Baghdad, a popular Telegram channel that supports Sadr, showed people gathering around the embassy around 1 a.m. on Thursday (2200 GMT on Wednesday) and storming the embassy complex around an hour later.
Later videos showed smoke rising from a building in the embassy complex. Reuters could not independently verify the authenticity of the videos.
It was not immediately clear if anyone was inside the embassy at the time of the storming.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)