Bulgarian Prime Minister Boyko Borisov has dismissed warnings from the US Department of State about a possible attack in the capital Sofia.



"The information... does not match reality," he has made clear, adding there is no danger to either "residents or guests of Sofia."



Domestic security agency DANS and the Interior Ministry have already checked the warning submitted to 112, the emergency hotline, Borisov has explained in a statement that follows a message by the US State Department citing the country's embassy in Sofia.



"The checkup found out it was all about unsettled love relations between a Bulgarian and a foreign national," he has added.



Borisov has also slammed US diplomats for exporting to the public "the information received by their Bulgarian counterparts" and for doing so in an "absolutely unacceptable way".

The US State Department's message came separately from a travel alert issued on Tuesday in the aftermath of the deadly attacks in Brussels claimed by the Islamic State (IS) group.

The warning about Bulgaria was published on the Facebook timeline of the department's consular section late on Wednesday Bulgarian time (EET). No follow-up comments have been published as of 11:00 on Thursday.

Commenting on the developments earlier on Thursday, the Interior Ministry's Chief Secretary Georgi Kostov said society had growing "more sensitive" to any possible threats after the Brussels attacks and that was the explanation for an increased number of warnings submitted by authorities.