Bulgarian Prime Minister Boyko Borisov has denied any direct connection between the move to expel Turkish national Abdullah B?y?k and efforts to avoid an increased migrant inflow into Bulgaria.

B?y?k was handed over to Turkish authorities after being denied political asylum, but in contravention of a court ruling and in breach of national legislation, with the Ombudsman of Bulgaria and non-profit organizations not being present.

"It is unpleasant to find out they acted in possible violation of the law. I have ordered [Interior] Minister Rumyana Bachvarova to look into it. If someone is guilty they will be punished," Borisov has told private NOVA TV station.

But he has said the problem might have recurred systematically with other cases where people were handed over to Turkish authorities after crossing into Bulgaria, in a reference to people who arrived as a result of the migrant crisis.

"We have sent back [to Turkey] from the border 25 000 people since the beginning of the year, and 1000 [have been sent back] to Greece. All of them have been returned in the same manner," he has pointed out.

Borisov, speaking to NOVA, has shifted the focus to the need to address the migrant inflow into the country, which he has described as his "big concern".

"My concerns are linked to the issue of where the migrants will stay in the end... I am exceptionally concerned of what Bulgaria might be facing."

"We are not obliged in any way, I am not saying [I am acting in order] to avoid any provocation - I am not saying that was the driving force when institutions worked to take such decisions. But with Turkey we have to try to build the best possible relations. Even if the price is that they take all of their [G?len supporters'] heads away."

The PM's comment is an apparent reference to the expulsion of B?y?k, although he has not explicitly linked the handover to the migrant influx.

"We are facing an enormous crisis between Turkey and the European Union, a crisis in which our leaders are the harshest possible threats. The whole Europe is surrounded with fences at the moment. What does the threat of "We will flood Europe with refugees" mean? This means: "We will flood Bulgaria," Borisov has opined, quoting threats issued by Turkish leaders that the migrant deal will not be observed if Turkey is not granted visa liberalization.

"My big goal is to make sure Turkey will treat Bulgaria differently than other countries in Europe, since if Turkey becomes an unsafe state, Bulgaria remains the closest safe state along the migrant route and 400 or 500 000 will be returned to Bulgaria as the safest country. These decisions are made by a nod."