The Bulgarian parliament on Thursday unanimously voted in favour of authorizing the army to police the nation's borders and keep migration flows under control.
All 137 lawmakers attending the vote backed the measure, which allows the government to deploy soldiers to the Turkish border with police authority.
Bulgaria lies to the east of the main corridor of migrants heading for Western Europe through Turkey, Greece, Macedonia, Serbia, Croatia and Slovenia. It registered 27,000 migrant arrivals in 2015, far fewer than its neighbours.
On Wednesday, Bulgaria allocated 35 million leva (20 million dollars) for the expansion of a 30-kilometre fence built in 2014 along the Turkish border.
Of the 130 kilometres planned, 60 kilometres of fencing have so far been built at the 275-kilometre-long Turkish-Bulgarian border.
The poorest country in the European Union since it joined in 2007, Bulgaria has a poor reputation among migrants, who frequently claim rights violations and abuse.