SOFIA: Several dozen schools across Bulgaria were ordered shut on Monday and Tuesday after receiving emailed bomb threats with suspected links to Russia, police said, reports AFP.

"The main lead of investigators is that these are hybrid attacks somehow linked to Russia," Interior Minister Ivan Demerdzhiev said.

One such message seen by AFP read: "There are TNT charges placed in all schools. Soon all your schools will explode. I hope you die."

The prosecutor's office said it was probing a crime against the republic, or terrorism, and was working to establish the source of the threats.

The alerts prompted the evacuation of dozens of schools in the capital Sofia, the Black Sea cities of Burgas and Varna, Sliven, in eastern Bulgaria, and Pleven, in the north, causing panic among the public.

So far no explosives have been found in the schools.

In total, 102 bomb threats have been recorded since Monday.

Yet, voting would go ahead as planned unless some real threat were to arise, Demerdzhiev said.