Bomb threats were emailed to the Defence Ministry in Sofia on 5, 6 and 7 October, but staff were not evacuated, defence minister Dimitar Stoyanov said.
He was replying to a question from MP Ivelin Parvanov of the Vazrazhdane party. Parvanov asked whether the threats against public buildings and offices in early October also targeted the ministry, and whether staff were moved out. He called them a "series of bomb threats".
The emails went to work addresses listed as contacts on the ministry's website. Stoyanov said the building at 3 Dyakon Ignatiy Street was checked and searched.
Another 9 email threats went to state kindergartens in Karlovo and Stara Zagora, which come under the Military Clubs and Military Recreation Executive Agency. Staff there were moved out and the buildings were put under guard.
After each threat, the ministry worked with Interior Ministry officers, who searched and checked the buildings and drew up reports.
It is not known who sent the emails or from which IP address. All the information has been passed to the organised crime directorate (GDBOP) and the Interior Ministry.