Barred from Britain, detained in Belgium, beaten with sticks in Sudan. The alleged torture of migrants from Sudan’s Darfur region started within hours of their enforced homecoming following an ill-fated attempt to start a new life in Europe.

“They picked me up immediately after landing in Sudan, interrogated me for hours and struck my feet with sticks,” according to one of the men quoted by local media and confirmed by a researcher who listened to the account. “They only released me two days later. I was so scared that I lay in bed at home for three days.”

He was one of nine men deported from Belgium to Sudan after being detained in an operation against illegal immigrants in the capital, Brussels, last year, according to a lawyer with knowledge of the case.

Sudan had been pre-warned about the arrivals as the Belgian government allowed the autocratic regime of Omar Al Bashir to screen the detained migrants.

Sudanese officials were invited into a restricted detention centre where they bullied the men and threatened reprisals against their families unless they returned to the African country, the Tahrir Institute for Middle East Policy has reported.

When they returned to Sudan, at least two men were beaten, detained for days and then released with restrictions on their movements and political activities, director Koert Debeuf said.

The revelations triggered a political crisis in Belgium – but is just the latest example of extreme measures taken by European governments to deport people or discourage them from entering countries in the face of public hostility to mass migration.

“This is crossing a red line of human rights and international law,” said Mr Debeuf. “This means that governments are using practices that are against the law.

“I think a lot of European countries’ NGOs are now thinking: what have we done in our own countries? I would imagine that many countries are crossing red lines.”

The moves to restrict the movement of refugees and asylum seekers follows a succession of electoral successes for anti-immigration right-wing parties across Europe, prompting mainstream parties to follow suit with harsher policies targeting newcomers.

The Danish government has passed a law that would allow police to seize the assets of refugees when they crossed the country’s borders. The right-wing vice-chancellor of Austria has floated the idea of imposing a curfew while housing refugees in military camps during applications for asylum.

While in Germany, anti-immigration MPs – emboldened by a strong showing in national elections last year – have called for medical tests for unaccompanied children to confirm their ages before they are accepted into the country, despite complaints from doctors that it would represent a violation of medical ethics.

“We have always criticised [Donald] Trump and his populism but we have mini-Trumps in Europe,” said Alexis Deswaef, a barrister and president of the Belgian Human Rights League who challenged the Belgian government’s repatriation policy in court. “They are playing on the fears of Europe to push their very right-wing policies.”

He said nationalist politicians in Belgium had focused on the threat from migration and terrorism in their push for votes. “They are putting all their energy into saying that the ‘danger comes from outside. We have to close our borders’. And they are among the most popular politicians in the country.”

The surge of mass migration into Europe was driven by war in Middle East and North Africa. More than one million migrants and refugees travelled to Europe in 2015, the majority of them heading for the continent’s richer states in Germany, Sweden and Britain.

In the three years to 2017, more than three million new asylum applications were made in European Union countries, according to the UN’s refugee agency.

Local politicians have complained that the migration has put pressure on health and other public services, and contributed to tensions over jobs.

Italy and Greece have shouldered a disproportionate burden owing to their Mediterranean locations but consensus efforts to share the impact of the new arrivals have failed. More than 20 countries have failed to fulfil a quota of refugees in their countries agreed by the European Union.

The intra-European rivalries have led to initiatives to try to prevent migrants reaching Europe in the first place.

Italy struck a deal in the summer with Libya to stem the flow of migrants and the EU signed an agreement with Turkey in 2016 that saw most of those fleeing the region returned to camps in Turkey.

The agreements prompted protests from rights groups including Medicins sans Frontieres (Doctors without Borders) – which rescued refugees travelling in leaking boats from the Mediterranean - which has refused to accept EU funding for 18 months.

“We couldn’t accept the money while their policies were funding or causing a lot of the issues we were treating,” said a spokeswoman for the charity.

The repatriation of the Sudanese migrants from Belgium was the natural conclusion of a series of decisions by European government to limit the impact of the migrant crisis on their own economies.

Under pressure from Britain, France in October 2016 razed the so-called ‘Jungle’ – a squalid mass encampment of some 10,000 people near the French coast of Calais, and a major gateway into the UK.

The destruction of the camp shifted the populations to other parts of the European Union, including the Maximilian Park in Brussels, where some 1,000 people were living in makeshift accommodation, said Mr Deswaef. The population included some of the Sudanese, who were rounded up following a ‘clean-up’ pledge by popular politician Theo Francken, the anti-immigrant minister in charge of asylum.

Mr Francken appears to have survived demands for his sacking amid fears that his departure would bring down the government and sparked new elections focused on migration.

Concern over migration contributed to the UK’s decision to leave the European Union and the record share of the votes secured by France’s far-right leader Marine Le Pen in 2017 presidential elections, according to analysis by former British premier Tony Blair’s Institute for Global Change.

Further elections this year are set to see the rise of anti-immigrant parties following varying levels of success in the Netherlands, Austria and Germany in 2017.

In Austria, the far-right populist Freedom Party is part of the ruling coalition. In Germany, the anti-immigration Alternative for Germany (AfD) populist party emerged as a major political player following an election fought on immigration issues, and left the previously imperious Chancellor Angela Merkel scrabbling to form a coalition government.

The successes have emboldened some of Europe’s more pugnacious right wingers, signalling further restrictions in parts of Europe. In a sign of the new hostility, Viktor Orban, Hungary’s prime minister, used an interview this week to defend his country’s refusal to accept refugees for resettlement and described them as “Muslim invaders”.