Orban denounced as insulting to Hungary's honour a report presented to the Strasbourg assembly that accuses his government of posing a "systemic threat" to the democratic values on which the European Union was founded.

MEPs will vote on Wednesday on whether to launch a procedure that could lead to unprecedented political sanctions against Hungary, and deepen the continental divide between centrist pro-European parties and populist anti-migrant forces.

"Whatever your decision will be, Hungary will not accede to this blackmail," an angry Orban told the lawmakers, whom he alleged had already made up their mind to activate article seven of the EU treaty and seek measures to restrict his government's voting rights.

"Hungary will protect its borders, stop illegal migration and defend its rights," Orban said, accusing EU elites of wanting to punish Budapest for its anti-migrant stance.

Budapest argues that its anti-migrant measures and defence of sovereign rights are in tune with the mood of European voters -- who will elect a new parliament in Strasbourg next May.

But Judith Sargentini, who is spearheading the vote on whether to take action against Hungary, told fellow MEPs that the time had come for them to make an "important choice" after eight years under Orban.

"Will you let it happen that a government... violates the values on which this union was built without consequences?" the Green MEP from the Netherlands asked.

"Or will you ensure that the values of this union are more than just words written on a piece of a paper?"

Her report voices concerns about the Hungarian judiciary's independence, corruption, freedom of expression, academic freedom, religious freedom, and the rights of minorities and refugees.

- 'Duty to stand side by side' -

Addressing the parliament ahead of Orban, Greek leftist Prime Minister Alexis Tsipras said: "Pro-European forces have a duty to stand side by side. We should not let Europe slide back to the past."

Opposition to Orban's vision does not just come from the left.

There is disquiet in the main centre-right parliamentary group, the European People's Party (EPP), about his position, despite it including his Fidesz party. Party leaders said they would announce their stance later Tuesday.

If the motion passes it would be the first time the European Parliament votes to take steps under article seven of European Union treaties, which could ultimately deny Hungary its EU voting rights.

Last year the European Commission, the EU's executive arm, launched similar steps under article seven against Poland over its alleged threat to the independence of the courts.

Poland's ally Hungary has pledged to veto any move to impose such penalties on Warsaw, which would effectively block the measure.

Commission Vice President Frans Timmermans told the parliament that his colleagues shared the concerns of the parliament about Hungary, but did not indicate whether he thought Budapest had crossed the threshold for invoking article seven.

It is also not clear whether Sargentini's push will win the necessary two-thirds support of the assembly.

While Orban's actions have provoked opposition, they have been applauded by populists elsewhere in the EU, with several prominent far-right figures floating the idea of a pan-European populist alliance ahead of next year's elections for the bloc.

- Report 'insults Hungary' -

The Commission, headed by Jean-Claude Juncker, an EPP member, has repeatedly clashed with Orban's government, especially since Budapest refused to admit asylum seekers under an EU scheme launched at the height of the migration crisis in 2015.

In July, the EU executive body warned it could take Budapest to the European Court of Justice over laws which call for up to a year in prison for anyone assisting an undocumented migrant.

The top EU court could impose fines, which would be less drastic for Hungary than losing its voting rights.

Orban said his government had sent all the MEPs an 108-plus page rebuttal of Sargentini's "false" charges.

"The report in front of you insults Hungary and insults the honour of the Hungarian nation," he said, adding his country was a proud Christian nation that had stood up to the former Soviet Union.