A rising tide of anti-migrant misinformation has flooded Bulgaria, stoking rallies and xenophobia ahead of Sofia's partial accession to the European Union's visa-free Schengen zone.

After more than a decade of talks, EU members Bulgaria and Romania finally got the green signal in December to join the Schengen zone, but only for air and sea travel, from the end of this month.

The move came after Austria lifted its veto. But in exchange, Vienna insisted that Bulgaria and Romania take back asylum seekers who entered Europe through those countries.

The bloc's so-called Dublin regulation stipulates that migrants must apply for asylum in their first European port of call.

The pro-Western government in the EU's poorest country has consequently faced attacks both from the left and the far-right.

In January, the leader of the pro-Russian Vazrazhdane party Kostadin Kostadinov, said Bulgaria could become "the world's biggest refugee camp".

Some far-right politicians posted videos on social media they said showed "migrants beating up young Bulgarians" in Sofia. Police, however, described the incident as an altercation between two rival Bulgarian groups.

Security has been stepped up in the capital and at refugee centres after several incidents targeting foreigners and anti-refugee rallies.

"There is no migration crisis, but a crisis narrative that poses a real threat to security," said Ildiko Otova, a migration expert and lecturer at Sofia University.

Unlike most Western countries, the majority of Bulgarian politicians were choosing to get involved, she added.

'Penal colony for criminals'

Bulgaria is part of the EU's eastern border, with Turkey to the southeast.

It has become a gateway into the bloc for rising numbers of people over the past two years, despite increased patrols along its 234-kilometre (145-mile) barbed-wire fenced border with Turkey.

Most of the migrants -- mainly from Afghanistan, Syria and Morocco -- do not stay long in Bulgaria and move instead to Western Europe.

After Germany deported about two dozen people to Bulgaria, the Socialists accused the government of rubber stamping a "penal colony for criminals, murderers, rapists and money launderers".

German authorities said the only known criminals among those deported were some Bulgarians released after having served their sentences in Bavaria.

The others were 18 Syrians -- including children below the age of six -- none of whom had been convicted of serious offences in Germany.

'Playing on people's fears'

Last week, Bulgaria dismissed opposition claims of "unprecedented migratory flows" into the country.

Relatively speaking, Bulgaria has been spared given that more than one million asylum applications were registered across the EU in 2023 -- a seven-year high.

According to official Bulgarian figures, as of 11 March, 190 had been transferred back to Bulgaria so far this year under the Dublin rules. In the last two months of 2023, the figure was 127.

Bulgarian officials say its reception centres for asylum-seekers are only 43 percent full.

The government has accused some political  parties of "inciting hatred and insecurity by spreading false information".

It also suggested that the Kremlin might be behind this with its "predictions of chaos and destruction".

Pro-Russian websites have picked up on and publicised most of the recent claims concerning migrants.

Politicians from smaller parties with a pro-Kremlin stance even went to the airport in a bid to show planes allegedly carrying "hordes of migrants", posting photos in an attempt to back up their claims.