Security has been heightened in places where many people gather in Bulgaria on Sunday following reports that police are looking for two suspected terrorists allegedly linked to Islamic State (IS) group, bTV channel reported.

Police has launched a search for a man and a woman, bTV said, citing sources.

Photographs of the two had been sent to the regional police directorates across the country. Police has stepped up surveillance at key transport hubs such as airports, rail and bus stations.

Security was heightened at the Spirit of Burgas music festival last night.

It was not immediately clear when and how the two suspected terrorists had entered Bulgaria.

Police are looking for Mimo Popescu, a Romanian national, and Ezida Elham, a French citizen of Iranian descent, 24 Chasa news daily said citing police sources.

There has been no official confirmation of the media reports yet.

The Bulgarian authorities were tipped about the two suspected terrorists as part of exchange of information with partner security agencies, 24 Chasa said.