SVILENGRAD, Bulgaria -- After spreading turmoil and desperate refugees across the Middle East, Syria's brutal civil war has now leaked misery into Europe's eastern fringe -- and put a spring in the step of Angel Bozhinov, a nationalist activist in this Bulgarian border town next to Turkey.
The local leader of Ataka, a pugnacious, far-right party, Mr. Bozhinov lost his seat in the town council at the last municipal elections in 2011 but now sees his fortunes rising thanks to public alarm over an influx of Syrian refugees across the nearby frontier.
Membership of the local branch of Ataka, he said, had surged in recent weeks as "people come up to me in the street and tell me that our party was right."
Ataka, which means attack, champions "Bulgaria for Bulgarians" and has denounced Syrian refugees as terrorists whom Bulgaria, the European Union's poorest nation, must expel. An Ataka member of parliament has reviled them as "terrible, despicable primates."
With populist, anti-immigrant parties gathering momentum across much of Europe, Ataka stands out as a particularly shrill and, its critics say, sinister political force -- an example of how easily opportunistic groups can stoke public fears while improving their own fortunes.
The influx of Syrian refugees has sown divisions across the European Union as the refugees add burdens on governments still struggling to emerge from years of recession. But Bulgaria is perhaps the most fragile of all the EU's 28 members. Modest as the numbers of refugees are here, the entry of nearly 6,500 Syrians this year has overwhelmed the deeply unpopular coalition government and added a volatile element to the nation's already unstable politics.
Violence in Syria that has stoked the spread of refugees continued Sunday. Syrian government aircraft dropped barrels packed with explosives on opposition-held areas of the contested northern city of Aleppo on Sunday, leveling buildings, incinerating cars and killing at least 37 people including 16 children, activists said.
The arrival of the refugees and public fury over the stabbing of a young Bulgarian woman by an Algerian asylum seeker "has opened the floodgates" for far-right nationalists, said Daniel Smilov of the Center for Liberal Strategies, a policy research group in Sofia, the capital. "They see this as their big chance."
Alarmed that Ataka's rhetoric is stoking sometimes violent xenophobia, a group of longtime Syrian residents of Sofia recently filed a formal complaint against Ms. Tasheva with the country's Discrimination Protection Commission, which said it was examining the matter. Ms. Tasheva declined to be interviewed.
Mohammad Albramawi, a Syrian computer expert who emigrated to Bulgaria years ago and helped initiate the complaint, said he had received threatening telephone calls and was so intimidated that he had stopped speaking Arabic outside his home.
"I have lived in Bulgaria for all these years," he said, "and now I am frightened for the first time."
Nikolai Tchirpanliev, a retired army colonel recently appointed to head the state agency charged with taking care of the refugees, said that the Syrians had helped wear out their welcome by complaining too much about stinking, clogged toilets and other problems in the camps and holding centers.
"It is like when the Huns came to Europe," he said, comparing the influx of Syrians to the wild, nomadic warriors who conquered much of Eastern Europe in the fourth and fifth centuries.
Amnesty International and other groups that criticize conditions, he said, should stop condemning the Bulgarian authorities and "ask, 'Why don't these people know how to use toilets?' "
Associated Press contributed.