A Greek MP said to be the second in command of the far-right Golden Dawn party has surrendered after authorities arrested the organisation's leader and other key members on charges of running a criminal gang.

Christos Pappas, the party's parliamentary spokesman and unrepentant holder of many of its most hardline views, handed himself over to police more than 24 hours after an unprecedented crackdown on the neo-fascist group began.

Appearing at Athens's central police headquarters in a taxi, the politician insisted the vehemently anti-immigrant party would "survive … the political persecution" it was being subjected to.

"I present myself voluntarily. I have nothing to hide, nothing to fear," he told reporters waiting outside the building where five other Golden Dawn MPs, including Nikos Michaloliakos, its leader, were taken into custody on Saturday. "The truth will shine. Nationalism will win. We will wage a non-stop political struggle and we will survive."

Like other members who appeared in court in handcuffs hours after their arrest, Pappas faces charges of murder, money laundering, extortion and intent to commit crimes.

His surrender came as officials in Europe, human rights groups, Jewish organisations and diaspora Greeks applauded the crackdown – the first to be conducted against sitting MPs since the collapse of military rule in 1974. Golden Dawn is often seen as Europe's most violent political group and has been blamed for more than 300 attacks on immigrants in the three years since Greece plunged into economic crisis.

"We praise the Greek government for taking bold measures to bring the leaders of Golden Dawn to account for their actions and to safeguard Greece's democracy," said Anthony Kouzounis, the head of Ahepa, an association representing ethnic Greeks in the US, the world's biggest diaspora community.

"The party's extremist principles and paramilitary-like tactics perpetrated upon any individuals of a free, democratic society are alarming and are a true threat to Greece's democracy."

Emboldened by its meteoric rise in the polls, the party had begun to look abroad, establishing branches in the US, Canada and Australia in the hope that it could capitalise on the anger of diaspora Greeks over the financial meltdown.

Before this month's murder of a Greek musician by a Golden Dawn supporter spurred the government into finally taking action, the organisation was scoring as much as 15% in opinion polls – more than double its vote when it took seats in Athens on the back of economic despair for the first time in June last year.

With six deputies now in custody, pending trial, the party's executive power has been severely diminished and its parliamentary presence cut by a third. Byelections are expected to take place to replace the deputies.

As he was being hauled before the court, Michaloliakos shouted: "Golden Dawn will never die."

But without its leader, the party seems rudderless. Tellingly, only a few hundred sympathisers heeded a call for support following the arrests, gathering outside police headquarters as the politicians were brought in.

The government of prime minister Antonis Samaras has pledged that the inquiry will continue. Arrest warrants have been issued for another 11 Golden Dawn members who are still at large.