Bulgarian Prime Minister Boyko Borisov has said his country will be forced to raise a fence along the border with Greece if the country does not uphold its "Schengen commitments".

At the inauguration of a renovated airbase in Bezmer, southern Bulgaria, Borisov has asserted that the country is not willing to build the fence, and there would be "no problems" if Greece stuck to its obligations.

Borisov has said it is Greece, and not Turkey, where an inflow into Bulgaria should be feared.

"People expect of us to defend the border," Borisov has told reporters.

His remarks come after Bulgaria had insisted that a controversial EU-Turkey agreement on curbing the migrant inflow into Europe should include guarantees no new migrant route would be opened up via Bulgaria from Turkey or Greece. The deal, however, did not match his conditions.

Earlier this week, Borisov reiterated that he expected the "main threat" of a possible migrant influx could originate from the unprotected, 494 km long border Bulgaria shares with Greece.

On Friday he told lawmakers Sofia stood ready to erect a light wire fence in case of urgency, an intention earlier confirmed by Defense Minister Nikolay Nenchev.