Sofia  - Two stores run by a Serbian conglomerate in Varna on Bulgaria's Black Sea coast were hit by bomb attacks early Thursday, police said.

Nobody was injured in the pre-dawn blasts which blew out the windows of the Piccadilly retail chain stores.

The chain is controlled by Delta, which has held an 85-per-cent stake in Piccadilly since 2007. Management said no threats were issued prior to the attacks.

The attack was still being investigated as yet there were no suspects or motives, police said.

Delta, which is owned by tycoon Milorad Miskovic, effectively monopolized the Serbian retail market and maintains many other interests.

Recently Miskovic has pushed to expand the retail business into former Yugoslav republics, including European Union member state Slovenia. (dpa)