Austria wants to prolong an expired exemption in an EU-wide plan on relocating refugees and asylum seekers from Greece and Italy.

On Tuesday (28 March), Austria's socialist-democratic chancellor, Christian Kern, said he would send the European Commission a letter with the demand and the reasons behind it.

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"We believe an exception is necessary for Austria for having already fulfilled its obligation. We will discuss that with the European Commission," he told reporters in Vienna.

The two-year relocation plan aimed to relocate an initial 160,000 people from Italy and Greece to other EU member states by September. So far, only around 15,000 have been dispatched.

Austria was given an exemption, which expired on 11 March and is now supposed to start relocating around 1,900 people before the September deadline.

Kern's move signals internal domestic political differences over relocation, but also casts an even bigger shadow over an already weakened relocation scheme.

The country's conservative interior minister, Wolfgang Sobotka, had told reporters ahead of a ministerial meeting in Brussels on Monday that Austria was ready to accept 50 unaccompanied minors from Italy.

But Sobotka was contradicted only hours later by the socialist defence minister Hanz Doskozil. Doskozil said Austria would not relocate anyone given its past efforts at the height of the refugee crisis. Around 90,000 asylum seekers came to Austria in 2015.

The two appeared to reach a compromise following an Austrian council of ministers meeting in Vienna on Tuesday, with Kern now asking for a second extension of the exemption from the scheme.

'Not without consequences'

But the EU commission on Tuesday said Austria must start its relocations.

"Austria is now expected to fulfil its legal obligations under the Council decisions to start relocating," EU commission spokesperson Natasha Bertaud told reporters in Brussels.

She said no country could unilaterally withdraw from the two-year plan.

"It can only choose to act outside the law, which we would find both deeply regrettable and not without consequences," she warned.

The Austrian move follows tense talks on relocation among interior ministers on Monday.

It also comes after a declaration on stronger integration, which was delivered by the leaders of EU member states over the weekend in Rome.

"The EU's migration policy rests on solidarity, and relocation is a very essential element of this," said Bertaud.

But the issue of solidarity and how it applies to broader migration and asylum policies has left sharp divisions.

Both Hungary and Slovakia are challenging the relocation scheme at the European Court of Justice in Luxembourg. Those cases were lodged at the end of 2015 but are yet to produce any hearings.

The court's advocate general is expected to publish his opinion in May, with a final ruling that could come before the end of summer, according to a source at the EU.