A senior figure in Bulgaria's Turkish community lashed out Friday at President Recep Tayyip Erdogan, in a further escalation of a spat ahead of elections in the EU country and a referendum in Turkey.
In a rare outburst, Ahmed Dogan, who headed the main party representing the Turkish minority in Bulgaria, said Turkey's vote on expanding Erdogan's powers was "madness".
"On April 16 neighbouring Turkey will hold a referendum to turn Kemal (Ataturk's) Republic of Turkey into a sultanate," the 62-year-old said in a statement.
Bulgaria is home to a 700,000-strong ethnic Turkish minority, a legacy of the Ottoman empire.
Turkey, its neighbour, is home to more than 200,000 ethnic Turks with Bulgarian passports who left Bulgaria during the communist era.
Around a third of those over 200,000 people regularly turn out for Bulgarian elections and are expected to cast ballots in the March 26 vote.
Sofia has accused Ankara in recent weeks of meddling in its election, summoning Turkey's ambassador and recalling its own envoy from Turkey for consultations.
Turkey's envoy openly backed Dost, a new party that split from Dogan's Movement for Rights and Freedoms (MRF) in 2016, which is the third biggest in parliament.
Ognyan Gerdzhikov, Bulgaria's interim prime minister, on Friday acknowledged there was a problem.
"There is a certain amount of tension linked to one of the political parties that receives backing from the Turkish side but we are taking measures to stop that," Gerdzhikov said.
The State Agency For National Security (DANS) said Friday that it had expelled one Turkish national from Bulgaria and withdrawn the right of entry and residence of two more after seeing them as "threatening national security".
One of the men was accused of inciting anti-Bulgarian feelings in regions with a mixed Bulgarian and Turkish population, the agency added.
A wider row is raging between Turkey and the European Union ahead of the Turkish vote, with a number of countries preventing Ankara's ministers from attending referendum rallies.
An angry response by Ankara has seen German and Dutch politicians called "Nazis" and Turkey threaten to scupper a 2016 deal with the EU to prevent migrants entering the bloc.
This could be a major problem for Bulgaria, the EU's poorest country, since it shares a 270-kilometre (165-mile) border with Turkey.