By Michele Kambas and Renee Maltezou

ATHENS With backing from a politician jailed for leading a party declared a criminal gang, Greek far-right groups swept up over 12% of the vote in Sunday's election, mirroring the rise of populist and ultra-nationalist politicians across Europe.

The surge of three parties with their ultra-nationalist views - including 'Spartans' which barely registered in polls until Ilias Kasidiaris from the banned Golden Dawn party endorsed it from his prison cell -- could swing public debate at home and prove a springboard in European elections.

While the centre-right New Democracy party of Kyriakos Mitsotakis stormed to victory in the June 25 Greek vote, winning 158 seats in the 300-seat parliament, the Spartans emerged as the fifth largest group.

Spartans and two more parties, Greek Solution and Niki - which together have 34 seats - view migration as a threat to Greece's national identity, believe LGBTQ+ issues undermine the sanctity of family and deeply resent authorities for forcing people to get vaccinated during the COVID-19 pandemic.

The deaths of hundreds of migrants when their boat sank off Greece while being tracked by the Greek coastguard has sharpened the debate over immigration. Despite mourning the tragedy, many Greeks want to halt the stream of migrants.

"The re-emergence of the far right is a byproduct of a political strategy of the New Democracy government which tried to appeal to the centre with an agenda of economic liberalism and, at the same time to the far right with an agenda of law and order and anti-immigrant discourse," said Akritas Kaidatzis, assistant professor of constitutional law at the Aristotle University in Thessaloniki.

EUROPE'S FAR-RIGHT RESURGENCE

Gains by the far right in Greece mirror a trend in several other European countries. Support for Germany's anti-immigrant AfD party is at its highest since the wake of Europe’s migrant crisis in 2018, in Italy a former far-right activist is prime minister and in Sweden a far-right party has joined the government.

Some analysts said it was unlikely the three parties would be able to define government policy. But they are expected to pressure Mitsotakis on LGBTQ+ issues, migration and relations with Greece's historic rival Turkey.

All three are expected to run in European Parliament elections next year.

First elected in 2019, Mitsotakis has been resolute in promoting LGBTQ+ rights but has himself taken a hard line on migration, prompting criticism from rights groups.

Some analysts said Mitsotakis's hard line on migration gave licence to a more xenophobic narrative from the far right.

However, some said ultra-nationalists had claimed the turf on the far right because Mitsotakis was shifting to the centre.

"I sense that it's less likely they will impose their agenda on him, and a lot more likely it will propel him more to the political centre," said Akis Georgakellos, political advisor and managing director of Athens-based communications firm Strategο.

"It's a given they will compete among themselves on who is the most extreme," he said.

TROJAN HORSE FROM SPARTA?

The Spartans party are led by businessman Vassilios Stigas. Despite a far-right agenda, it lacks the militancy of Golden Dawn, which was known for its torch-lit marches through Athens, vitriolic speeches and Nazi-like salutes.

In February, Greece's parliament passed a law banning parties whose leaders are convicted of crimes.

Yet Kasidiaris, Golden Dawn's former frontman, has shown he is still a force to reckon with, even from behind bars.

"I will vote, and support with all my strength the Spartans," Kasidiaris wrote on Twitter from his cell in the high-security Domokos prison after Greece's top court disqualified his group from contesting the elections.

Kasidiaris is serving a 13-year jail term for his leadership role in Golden Dawn, once Greece's third largest party. It was declared a criminal gang linked to hate crimes in a 2020 court ruling. Both convictions are being appealed.

(Reporting By Michele Kambas and Renee Maltezou, writing by Michele Kambas, editing by Edmund Blair and Christina Fincher)